Thanks for all of the great information. My pops ordered a new motor, tranny and transfer-case to drop into the 77. I stole the 454 out of it and the thing had transmission problems...Neither of us has the experience or time to invest in rebuilding the TH-350 or NP-203 (if there was a problem with it).
So now pops is going to have basically a new truck. Truck lived in California most of its' life so it's pretty clean and rust free.
The only stuff he has to worry about is brakes and electrical, otherwise he's going to have basically a new truck.