use a older chevy or gmc pick up frame ( K 4X4) 1978- 70 all the same style (long bed )make sure of wheel base you may need to make new cab mounts just replace floor to the year using it will take time but your not going stock original anyway place your cab first then the rest should follow good luck

before you take the first bolt loose spend an hour flat on your back measuring every up/down and twist then decide if it is the right way .