WROA675

Certainly not the only option, but a good one:
https://www.theantennafarm.com/catalog/index.php?main_page=index&cPath=342_343_347_993_1410
Thesa are made wtih LMR-400UF (Ultra Flexible) so easy to work with and come with N connectors.

The antenna gain will limit the frequency response across the full range of channels available as it will maintain a low SWR for 5 MHz on either side of the tuned frequency. As far as a unit to use for the base, I'd go with one that is rated at 50W on the UHF frequencies. Brand isn't as important as are the specs for receiver sensitivity, the higher the value of the number the better.  -115 is better than -110 or lower absolute value. The bandwidth affects transmit primarily as SWR has little to no effect on receiving.

Uh, no
Bad catch on my part, I didn't look at the modes being used
LAPD is P25, oops,
My bad is a severe understatement [hanging my head in shame]
At least LASO & LACoF are a mix of narrow band & wide band FM
Send me to my room to reread Frequencies & Modes 101 again

Every SHTF radio in SoCal should also have 450.7 MHz programmed into it (on a "scan-off" setting), so that when, for example, an earthquake hits, you can get immediate access to KNX-AM (1070 Hz), which is a great source for emergency information.

Thank you for sharing your input and experience. The different perspective helped. I'm glad I posted here, gathering all these knowledge nuggets, so I can be confident that when I'm ready to order, it will be everything I need and nothing I don't.

RG8x is better than RG58 but is still terrible for UHF - spring for the LMR400; it'll give you a noticeable boost in performance. It's worth the cost: https://abrind.com/product-category/abr400-solid-ultraflex-assemblies/
I can't comment first hand on the antenna; but the Browing BR-6353 works well at GMRS for what it is, it's only slightly more than the TWAYRADIO brand: https://www.theantennafarm.com/catalog/index.php?main_page=product_info&products_id=3580&gclid=Cj0KCQjwkbuKBhDRARIsAALysV7PYMkBxYiCxyoQ5dSVENW9I2CnZc0eMgrFmNlvt_oP7ufbQQW9qdYaAiPhEALw_wcB. It's fully welded and pre-tuned, it's surprisingly tough for how cheap it is. I recommend getting away from Amazon when shopping for radio stuff.
Bonus points for the type N connectors too - while PL259's are also called "UHF" connectors it's because when they were designed UHF was anything above 30mhz; Type N is mechanically a better and lower loss connector, and are better for weatherproofing too.
edit:
Back on the coax; you're putting up a 7.1dBi yagi antenna, with 50' RG-8x you will lose 4.246db of that gain for a net system gain of 2.9db.
In contrast; with the LMR400 - you're 'only losing' 1.371dB for a net system gain of 5.7dB
For the hell of it - using RG-58 results in a net system gain of 0.2dB; it'd almost completely negate the benefit of your antenna to an isotropic radiator (which is below the performance of a basic dipole as it is already).
For reference; a basic dipole 'unity gain' antenna is 2.15dBi (aka 0.0dBd)
see: https://www.qsl.net/co8tw/Coax_Calculator.htm

RG58U is a wrong cable to use for 50' length. You reduce power of your signal 10 times. Use LMR-400. Coax attenuation chart:  https://www.w4rp.com/ref/coax.html
If you have to have thin cable, at least opt for LMR-240 or RG8X.

Quick update. With some help and the GM30, I was able to hear 484.96250 (LA County Fire Dispatch), so that's good to know going forward. It was shared that many of the emergency stations may be using digital tones. Gonna play around with it some more tomorrow. 

The GM-30 has an SMA-F fitting on the radio, which requires an antenna with an SMA-M connection. The NA-771G from Buy Two Way Radios is available in both SMA configurations, plus BNC, and is specifically tuned for GMRS frequencies. Most Baofeng radios require antennas with the SMA-F connection, so if you order something different that doesn't specify the connector, it probably won't work on the GM-30.
There is also a shorter NA-701G antenna you can buy, but some reviewers have said it doesn't work much better than the stock antenna. I haven't tried it, so I can't comment on that aspect of it from my own experience. It has the advantage (as does the stock antenna) of being less intrusive than the 771G due to its shorter length.
If you're going to use the radio in a vehicle, I'd recommend a magnet-mount (or permanent mount) external antenna for better performance. Even a cheap, but properly tuned, mag mount will improve performance substantially over using a whip attached to the radio inside the vehicle.

When a comment is underlined, it usually means it is a link you can click on:
Nagoya 771G
in this case it takes you to BuyTwoWayRadio
more later

there is a tiny torx/allen screw inside the hole.. just loosen it and you can then unscrew the antenna.  If you are certain there is no setscrew there, then you should be able to just unscrew the antenna.
Ive done it with both my GM-30 and my Tidradio TD-H5 which is basically the same thing.

CSQ is carrier squelch (aka no tones). Hearing not a peep, my first thought is to double check that tones are really off though.
Besides that, it looks like their setup doesn't exactly lend itself to monitoring....radio reference indicates they don't repeat the mobile traffic (unit to dispatch), they talk direct to dispatch on the input frequency (so you'd need to monitor 2 channels to get both sides of a Convo). Probably aiding that, it looks like after the initial contact, they move off the dispatch channel to one of the tac channels. 
The limitations of the HT antenna, especially indoors may also be playing into it as well, given you mention that even the nws reception is spotty.

I just looked at the specs for your GM-30 on Radioddity's web site: 
Specifications:
Default Channels: 30
Channel Capacity: 250
Battery: 1500mAh, 7.4V
Output Power: 0.5W / 5W
Tones: 50 CTCSS / 104 DCS
Tx Frequency Range: 462.5625-467.7125 MHz
Rx Frequency Range: 65-108 MHz, 136-174 MHz, 400-470 MHz
Your UHF receive is 400 - 470 MHz, it doesn't tune high enough for those departments
According to the Radio Reference.com data base for LA County https://www.radioreference.com/apps/db/?ctid=201 
LACoF starts at 470 MHz
LAPD uses 484, 506 & 507 MHz
LASO runs between 482 -485 MHz
LAFD isn't even in the ball park, it uses higher 800 MHz channels
Have you updated the firmware & software to the current version? Maybe that will give you expanded receive

To make a complicated subject a little clearer, the intelligence in an FM signal (GMRS is FM) is carried by the shifting of the frequency within its channel. Wide band signals can shift a total of 5 kHz while narrow band signals can shift only half that amount. The result is two-fold, the signal sounds softer and additional channels or paths for transmission can be created between the wide band channels.

His Midland video was first and before he reviewed the Radioddity.
I will watch 12.16 later but this disadvantage is less pronounced at home, especially where you live, but annoying if in the future more repeaters use the same frequencies, such as 462.700 in SoCal.
Split tone is where the input tone of a Repeater is different than the output tone of that repeater.  That makes it more difficult for users to self-discover the input tone and hence the repeater owner might want to keep out the riff-raff!
Narrowband is to be avoided at all costs: except where it is mandated by the FCC for the so-called low-power (0.5 watts) interstitial channels 467.xxxx Channels 8-14.
He was simplex with his 10 mile away friend.
You would need a home Power Supply that provides 12 volts DC with plenty of amps: Randy recommends one at BuyTwoWayRadios.com for about $150.  Mine was about $90 when Ham Radio Outlet was still in business in Burbank; now their closest is in Anaheim, and you want to avoid shipping costs as they can be heavy.
Check out hamradio.com and the Powerwerx website, too.

Click on your Profile photo here, click on Edit Profile near upper right and then scroll down to Location.

And for $25, a cup-mount holder will save you drilling holes which is a perfect addition to this units ability to plug into the cigarette lighter for easy install, removal and reinstall.
Cup-Holder mount

I don't know much about that radio, but before your ability to refund it expires, be sure that it has the ability to have multiple channels with repeaters on the same frequency but with different tones.
This is essential in a mobile unit or HT where you will be operating outside your normal coverage area.
For example you drive down to San Diego and want the ability to communicate through various repeaters that reside on the same frequency.
Take a look at this $99 retail Anytone AT-779UV a/k/a Radioddity DB-20G (retail $109) for its similar features to what you want but with over 100 channel capability:
Radioddity DB-20G on Amazon

The MTX speaker is pretty weak. I run an external CB speaker and it works well. I jammed mine under the dash. Being the Andy 2 is pretty small you could mount that via bracket then use velcro or double sided tape to hold the MTX to the bottom if you want it there. 

Thanks.  The range and reception seems pretty good, once I changed all bands from narrow to wide.  Still, I ordered an Nagoya NA-771 antenna to see if that further improves things.

This one below was not listed as a repeater in the mygmrs database, but a comment in reply to a listing, so let me make sure I understand it.

First the comment...

New Socal Free Speech Repeater...
Serving Orange, San Diego,LA and Inland Empire.
Located high in the Cleveland National Forest (4000ft)
462.550 DPL 306 Output
467.550 DPL 306 Input
For mature audiences only...Brought to you by the folks that bring you the L.A. Maga 725...
MAGA 550 ! Loud and big in Socal.

So one would tune to Repeater Channel 1, correct?  The DPL 306 is basically a privacy code, true?  Would some form of CTCSS code be required to potentially access that repeater, and if so, how would one locate it?  Seems if he wants people to use the repeater, he would provide that information, unless I'm missing something.

Also, on a separate note, if anyone figures out whether or not my Pofung P15UV is simply a rebranded Radioddity GM-30 or something different let me know.  Here's the radio in question, for anyone interested, which I've posted as an affiliate link, but that's not why I'm sharing it.
https://amzn.to/2Y7VNlv
 

WELCOME to GMRS!
If it were me, I would go up on the repeater and ask permission there and if they are testy, tell them you wrote and no reply.
Since there are only 8 GMRS repeater pairs, I like to SCAN and if I hear obvious repeater communications on those channel, I take notes.
Can your rig "scan" CTCSS tones, that is, tell you what tone is being used by the repeater users when they transmit.  This is a very handy feature and I may buy another HT just to get that feature! My "ham radio" Yaesu FT-857d can do that feature for me now, but it cannot transmit on the GMRS channels; only receive.
It is necessary to know the repeater tone for your transmissions to be "heard" by the repeater.
Using tones for your reception is optional; they help eliminate interference to you from other repeaters on the same frequency.
Since I am an explorer, I never use reception tones, so I can always hear what other activity is present and then do some tone and location research about the others I hear.
You have, of course, looked at the San Diego area of the map here on MyGMRS?
UPDATE: the previous poster, OffRoaderX, has a terrific series of YouTube instructional videos about GMRS and other topics: Search NotARubicon on YouTube and Subscribe and Thumbs Up him, if you like his videos!

Just turn to channel 3 on your handheld

I’m on my way to that area now
 
I’m on my way to that area now
 
Turn turn on channel 3

WELCOME!
Make sure that your channels have NO receive CTCSS tones set, so that your receive is wide open to listen to whatever is transmitted on that frequency.
I have the clone of your Radioddity, the Pofung P15UV, purchased specifically so that I could use Menu items 30 and 31 to scan for CTCSS and DCS tones transmitted by others to gain access to Repeaters.
Take a drive up to a hilltop area and see if anyone comes back to your transmissions then; you'll have better range, the higher you are! They may not hear you still, if they have Receiver tones set up to block out unwanted transmissions -- You will have to use Menu Items 30 and 31 to see if they are expecting transmission tones and even this will not work, if they use different tones for XMIT & RCVE
Check out these repeaters for SoCal - Los Angeles:
Crestline: 575 ("462.575"; Transmit Tone = 67.0) if you are on the more Eastern side of the County
Mt. Disappointment 600 (167.9)
Mt Harvard 625 (151.4)
Club 650 (107.2) Especially in the San Fernando Valley
Ranchino 700 (D271N) If you are in the Northern Inland Empire
RT 725 (100.0) Be careful; there are Bozos on this bus! 
Remember to program these into Channels 31-54, so that your HT knows to transmit up on 467.xxxx and yet receive on 462.xxxx*
The Morse Code is FCC required Identifiers of who owns the Repeater.
Check out this YouTube video for background:  We like to support the socially-challenged! ?
*I assume you have the updated Radioddity firmware to allow these extra DIY Repeater channels.  Turn off power, hold down the button just below the Push-to-Talk button and turn on power: a firmware number will briefly appear, such as 006.03.006, which is currently the updated firmware number.

PS: Take a look at the Anytone AT-779 a/k/a Radioddity DM-20G a/k/a Retevis Ra-25 for your truck ($99 to $129 retail).  I love mine:
18 watts
Cigarette lighter plug
I purchased a $20 mag-mount antenna and a $25 cup-mount holder for it: