Would there be any problem swapping my non-bose single disc/tape radio with a 6-disc changer? Did they make a 6-disc that was non-bose? Could I swap in a bose?

Yes I think you can, Keep an eye on my thread in this forum about GMs navigation radio. I have the bose in dash 6 disk head unit, and am looking to swap it for the NAV radio. Once I obtain one ( they are priced pretty steep ) my old head unit will be for sale if your interested.