Thank you all VERY much for your excellent feedback!
My car is a 1966 model year Coronet 500 and it still has it's original factory installed front bucket seats, with the only non stock items being a custom set of seat covers that I had made and installed back in 1990. Since I have already had Just Dashes completely restore my seats original metal back panels and lower side covers from their original black, to the factory offered pearl white, along with having a brand new set of Legendary's 1966 factory style seat covers in pearl white and the 66-67 seat foams and other needed seat restoration supplies, it looks like I will have to pass on trying to make a set of the 68-69 seat frames work with my 66 style supplies, as they appear to be even more different from each other than I had originally thought.
Man, no headrests, no locking seat backs, no factory shoulder belts and a steering column that looks to be built to spear you in the chest in a collision! Safety has come a LONG way since 1966!
Richard