Pretty straight forward. Just find a donor truck from about the same year as yours, and swap everything out.
Everything interchanges pretty easily, especially if you find a similar year. If you have the whole donor truck you can get the tranny, t-case, shifters, clutch/brake pedal assembly, steering column, clutch linkage, and driveshafts.
You will have to fab at least one hole for the clutch linkage to go through the floorboard, but on those older trucks the floor board is dimpled where the holes need to be. Also depending on the donor, you can just swap out the center hump in the floorboard that already has the hole cut for the 4-speed shifter.
You should also already have the holes in the frame so that the clutch linkage is a simple bolt up deal as well.