A while back I purchased a Tahoe involved in roll over. Blue cloth buckets, electric seats. Put in a 57 pickup rat rod project of customer. Everything was all self contained just needed to hook up power, then seatbelts. Everything worked out fine. Over 2 tons force in a head on, so make sure you use 3/8 or 7/16 grade 8 as mounting.
I think I used metric 12mm with red Locktite. I backed up the under mounting with 1/8 steel plates to add strength to floor pan. The last thing I would want would be to have the bolts pulled through the floor pan if or when a collision every would happen.
Many many years ago I was an EMT, the driver was killed because his son was behind him not wearing seat belt. Had same type of seat you describe in a full size car. The son was a good size kid of HS age and he hit the back of the bench seat, bent it and crushed his father between seat and steering wheel.
The dad was wearing seat belt and it locked and because the seat bent forward, was never designed to pivot, he couldn't move and couldn't breathe. By the time we arrived he suffocated and we tried CPR but unsuccessfully.
Just be very very careful with seat changes.
