From you guy's suggestion, I went ahead and looked into a CDM750 and a CDM1250 and I think duel 1250's will work perfectly fine for me. I noticed that they have additional pins but if im not mistaken, the outer 2 on each side can be disregarded and it should be plug-n-play. Ill have to compare the pinouts from the GM300 to the CDM1250 to make sure I dont fry anything, and just to be safe in knowing what im doing.
I have tried working with DOSBox on the GM300 but with everything I've tried, I got no luck. I tried it on Windows 7 and Windows XP, changing the serial port settings, trying different cables, and on and on. I really have exhausted my options with it and if I do get it working, learning how to program it will be foreign to me completely. Im sure ill miss some settings that might be a no no. Thats why im wanting a more modern CPS to tinker with and I have successfully gotten my hands on the Professional Series CPS for the CDM. Thank you for the heads up on the eBay listings. I know there can be some bad eggs on there. I usually go to my state surplus first to see if they have anything and that's how I got the GR300 to begin with. They do a good job wiping and removing any passwords on radios when ever they do appear.