If this is the biggest problem you have with this truck, consider yourself VERY fortunate. If you start messing with this, you will end up doing a frame up restoration. It may be piece by piece and take a couple of decades, but that's where you are headed.
Well, I got the brakes working tonight. It had no pedal, but the master cylinder looked relatively new, and the bleeders on the rear brakes were still shiny. I bled them out, and it has a good pedal now. It is a lot more fun driving around the meadow with brakes! I think the truck was restored not too long ago. The running boards appear to be NOS, as well as some other parts on the truck, and there is black blasting media behind the seat. Underneath the truck looks really clean in many places, with some grimier areas. Now I just have to put tail lights on it, and clean the fuel tank out and line it. H.