In my experience the main weakness in the brake systems is the master cylinder and lack of a booster. You likely don't need disc brakes and the associated cost. 3/4 ton trucks have large brakes and work well when properly set up. Rebuild the brakes with new cylinders, lines, shoes, & drums. Replace the master with a dual diaphragm booster and a dual master cylinder and you will be amazed how good they are.
Fred
