I know of Two trucks like that in my town. One I Just saw the other day on a trip to the boneyard. It was a 62 or 63. looked like a Dana 44 front, but with DRUM brakes. You think the drag link is a weak link on 73-91's, the drag link on this truck could not have been more than 1/2" in diameter. The truck is kind of complete, but most of the little items have been stripped from the cab. Front fender and engine were gone to. It was a 4 speed truck though.
The other truck is a 64 and it sits on a corner residential lot a couple of miles from my house. Complete, looks like it could drive, but I havent seen it move in the last year since I first seen it.
A Shop I deal with in Phoenix is working on a 63 as a restoration/play toy project. He already ditched the drum brake front axle for a disc brake D44 out of a 74 truck.
If one was to actually build one to drive and not be a 100% original show queen, I'd beef up the stock parts. The frames on those trucks were bigger than the 2wd counterparts. The eaton rears are strong, but like I mentioned the front end needs help.
They are out there, but you may have to buy the shell and frame from a boneyard and start from the bottom.