1988 - 1998 Chevrolet C/K (or GMC)seats fits quite well, that is what my truck had in it when I first bought it. Other than drilling four holes it's pretty much as easy as it gets.
http://i645.photobucket.com/albums/...rchased%20Aug%202008/65ShortStepSeat.jpgThe problem with using car seats is you will have to fabricate mounts to raise the seats up into a proper seating position. Additionally most automotive seats have headrests which, while functional and "safer", look hideous as viewed from the rear window.
Hope that helps.