You're going to have some major headaches finding those brake drums, and when (if) you do, the 14" brakes mean that you're stuck with running 18" or larger wheels. I owned a 59 model 3800, and considered switching to a later-model rear axle with smaller, wider brakes so I could use 16" wheels and tubeless tires. I don't think new drums are available anywhere, unless someone has started making reproductions recently. I sold my drums to another bolter on this site a couple of years ago, and then traded the rest of the truck for a 261 engine.
Jerry