The GP350's are some of my favorite Moto radios of all time. And I consider myself a fairly seasoned collector. I have a small fleet of them myself. Some interesting trivia: some versions are narrowband compatible, the accy connector is unique to the GP350, there are 2 and 16chan versions available, there's also a somewhat unusual DTMF keypad model. I have a pretty rare voice inversion board for the 350, would love to find a second one.
It will probably be hard to locally source a RIB, not to mention a GP350 programming adapter. I've had plenty of experience with alligator clips, blown fuses and heart-pounding, white-knuckled 'write to radio' sessions. If you think you may keep the radios a while, it might be worth finding someone to help you buy the ebay adapter. It's not impossible without the adapter but much easier and, considering you'd still need a RIB anyway, likely cheaper to boot.