You could use the stock chassis, with some modifications. I would suggest looking up information for the early Napco to see how they were set up. Advanced Adapters can help with the transmission/transfer case, they have an adapter that will allow for using an sm420 with a 205 t-case. You will have to put at least 12" lift to get axles to clear the oil pan in the front, the rear isn't really a problem for clearance at the bed. If you are concernad about axle with, Dynatrac and Curry can make you axles in thee withs that you want, but they will be expensive.
You may want to checkaround for Napco conversion parts, Jim Carter's would be a good place to start. You will find that most of the '54 and earlier will be 3/4 and 1 ton, 1/2 wasn't availible 'til '55. Something you may want to consider is finding a complete chassis for a later 4x4, that way you can get matched axles, transfer case, and possibly springs that you can adapt to the stock frame.
