There’s a company called yearone.com that sells all the components for folks wanting original. I think they are nuts because even when I was skinny the gm bench seat was as uncomfortable as it gets…
Squarebody floor is excellent (if not rusted). You can take some 1/4” flat bar that 2” wide and cut roughly 4” long iirc. Drill hole through the center and use that under the body at each needed location with flat washer, and mechanical lock nut under it and mount most any seat you feel comfortable- and drill your own holes.
Had to make a couple of those same plates as leveling plates inside once or twice.
When you make your own hole- you need the steel plate to sandwich your hole to disperse the load.
Me and a ton of friends all had square bodies and I can’t remember anyone who left the original bench in place. We used seats from Fords (i know, i know but they were cozy)- check out modern Expiditions/explorers. Toyota make some amazing bucket seats for us non skinny guys.- Sequoia are great.
If you can find someone who made the error of selling Hummer H1 seats (NOT HMMWV) they are very comfortable because they actually come from a high end bus manufacturer in Europe that was engineered by a couple doctors- I absolutely love my 95 hummer seats! Unfortunately the price is usually same as buying new custom seats.
Really the best suggestion is what we used to do:
Measure the raised part of the floor under the seat. Dont worry about the little bumps. Go to a junkyard and go seat shopping. Climbing in and out of the cars is a pain but that actually helps. When you sit down and wanna just rest a minute- thats a good sign that seat is cozy! Haha.
We had to hammer the angle of the mounting tabs up or down a little because everyone makes little floor bumps slightly different.
What many of the guys did was get little bucket seats that would sit too low- but we could weld, so we just built mounting brackets.
Long gone is the trend of buckets mounted on a pivoting plate so a lever allows you to spin the seat 90° to get out and back in easier than sliding across. But pretty sure the pivot things are still for sale for rv manufacturers if you choose.
No matter what you get- NOTHING will just bolt in and fit with the seat lower that I am aware of that won’t require some custom fabrication. Just remember a key thing- that seat mount needs to spread the load underneath the body so that if some idiot cuts you off into a decent crash- the bolts can’t rip through the body. And the factory little oval ones were barely adequate back then and often not adequate, and they are welded in. So you have to go bigger on your plates by a large amount.
