I put a set of buckets out of some furin car in my truck.I got a deal on them at a swap.The front mounts were verticle and the rears horizontal.First I measured everthing,height(front and back),distance from wheel,seatback to wheel,width,centerline.I pulled the original seats out and put the furin ones in their place.I found the mounts in back were close enough for the bolts to fit but were about 2 in lower than the original seat bottom at the back,so I used a piece of 1 1/2 square tubing cut to the width of the mounting flange on the seat and just drilled a couple of holes.I used new longer bolts and lined it all up by lightly bolting the rear down.
Then I measured the front mounts and found they were a lot narrower than the originals and set back about and 1 1/4.So I cut a piece of 1 1/2 angle to the width of the original bolt holes and drilled the angle so I could lightly bolt it in place.Since the front of the seat was lower I marked and then measured the angle to raise the front 1 1/4 .I bolted it all up and had new seats.The passenger side has a drop off in the floor (I never looked at a PU mines a Panel)I shimmed the outter about and in or so and it works well.
I really want to go back to the original buckets but since the PO used a couple of 2X's and some plywood for springs.....
I also now have power drivers seat.I spent about $20.00 on metal and such but some was donated.I gave $50.00 for the seats if memory serves so I have about $80.00 in the change.It lets me keep driving my truck while I try to find springs and such to rebuild/customize my originals.Here's a post of how mine are mounted.Just look them over and you will find an easy way to make them fit.BTWE I drilled one new hole in my floor.
http://www.67-72chevytrucks.com/vboa...ght=seat+stuff