Installed the front blazer spindles with the 2 piston calipers. Also installed the rear disc of a 97 olds bravado(mad my own caliper brackets). Rear is a 12 bolt Chevelle Have changed the prop valve to a 4WD valve. 7/8 bore g body master cylinder. System doesn't seem to flow enough fluid causing low pedal. Most of the time need to pump the pedal. Any ideas on a master cyl that would work good?