Here are some pics of a kit that was purchased from JC Whitney 10 yrs ago for my 79 supercab
rear seat lift block for p/s
This set up allows for 4" lift w/ seat set up and still have the 4" w/ the seat folded down for a solid platform. You also need to provide for extending the seat belts to accomadate for the seat being raised and also the latch assembly to lock the back part of the bench has to be either modified or relocated.