try this one http://www.speedwaymotors.com/1947-1954-Chevy-Pickup-Power-Brake-Pedal-Assembly,8903.html
Stock frame, S-10 Frame, Subframed Or???? With a stock frame the original pedal assembly works if you use a booster/master cylinder setup like Noname showed or build a bracket to mount the master cylinder. If you have the stock frame and don't have any pedal assembly the setup from speedway probably will run you less than gas for hunting a stock assembly or ebay and shipping will especially if you run an automatic. I don't have power brakes at this time and built a bracket that bolts on in place of the stock master cylinder and mounts a 68 C-10 drum brake dual master cylinder for my drum front and rear setup. I had to fab the bracket and build an extended brake pushrod that was stout enough so it wouldn't flex or bend.