Paul,
There is a thread kicking around somewhere on the site about converting from the Huck Brakes that your truck (and mine) currently have to the newer Bendix style (the one that came out in 1953/1954). They will still be drums, but the process looks to be very easy, with some minor modifications made to the Bendix backplate. You can even supposedly reuse your spindles and hubs, and, of course, your stock eight-hole wheels.
I'm not terribly sure that there's a reason for you to do the conversion, though. There really isn't any problem stopping a stock 3600 Pickup with the stock brakes, unless you've got the engine wound out well beyond the red line... and even then, she stops well enough with a well-maintained old-school Huck braking system.
All of the parts -- save the drums -- are easily purchased new through the usual vendors (American Classic, Jim Carter, Chevs of the 40's, The Filling Station) or your FLAPS. The brakes are very easily maintained -- much, much easier than modern setups. Don't let either of these two things deter you from keeping your stock setup.
If you need new drums or are planning on hot-rodding the old girl, then I would start looking into converting to something else. If you don't or aren't, I wouldn't bother. (Though, I think I'd find a half ton to hot rod -- parts are easier to find.)
~#~#~#~
Also, something to keep in the back of your mind: Discs will probably require some sort of brake booster. Discs are much harder to actuate on the power of your leg alone.