I haven't done that exact install, but have used modern seats. My best advice is to block the seats up to determine the height you want, then make some kind of mount that goes between the buick seat frame and your trucks floor. I used 4x2 steel tube, 2x2 steel tube, and angle iron That way if you need to change or adjust something in the future, you can just adjust the frame you made and the frame of the Buick seats are not messed with. I say this assuming you'll need to mount the seats high off the floor, since where you'll want to sit in your '54 is much higher than where you would sit in a 2004 LeSabre.


1946 GMC Pickup - S-10 Frame, 455 Buick, TH400, original patina.

My 46 GMC on Photobucket