We have a 65 C-10 with CPP disc kit with 6 lug rotors and 3" lower springs and shocks, Corvette 8" booster and master. It still has stock rear brakes, all new with an adjustable valve in the rear line. The pedal goes to the floor and the calipers only move a tiny bit at the end of the pedal travel. I bled it every where. With the line to the front unhooked the master only moves a tiny bit of fluid, again at the very end of the travel. I watched it as I tried to again bleed the master. Any suggestions?