I too, am a newbie, I have owned my 1954 6400 for tens days now. I have purchased several things, thus far from Ebay. As well as, other online dealers. My plan for the brake shoes and clutch is to have them relined when the time comes. Wheel cylinders have been my biggest issue thus far. I have not gotten that far into this project, still installing the floors. But ai have started the search nevertheless. Rebuild kits are fair enough, but you better put your big boy britches on when they show the price of the wheel cylinders, shewww, I almost soiled myself.
Other than that, most parts have been fairly.easy to locate. Although, I am having trouble locating the GM side view long arm mirrors for a dump bed....ah, the saga continues.
Mark