ONE thing to consider is that most late model bucket seats are a bit narrower than the factory buckets which came in those cars. Or other cars for that matter. You don't realize that until you measure the new seats. Whereas the older factory buckets had space between them and the console/buddy seats, the later model buckets actually rub against the factory console in their newer cars. Which ALSO means that the inner part that rubs the console is fabric rather than vinyl!
For decades, modern bucket seats have had side-impact air bags in them, too. Which would need to be deactivated/removed for use in a car that did not use such.
For bucket seats which have he seat belts included into them, when those seats came into use, the floor pan strength was increased a bit to handle the added forces of all of the restraint forces being focused on ONE area of the car's structure, rather than being spread out between the B-pillar mounts and the floorpan (as the magazines mentioned back then).
Just some observations as I looked for factory buckets to fit a 1970s non-Ford, non-Chry pony car I have, to replace the existing factory buckets, several years ago. I gave up.
Just some thoughts and observations,
CBODY67