I swapped over the 12b and front 44 to my '73 for the lower gears and lockouts. Ever since then I ain't had much of a brake pedal. The master cylinder had been borderline (the pedal leaked down when steady pressure applied) and I had to wring off the left rear line to the wheel cylinder (32 year old rusted) replaced wheel cylinder, new line to it too. So I replaced the master cylinder last Saturday (Bench bled MC) and did a thorough system bleed (used a quart of fluid - nasty black fluid removed) alot of air came out but..............the pedal still goes almost to the floor before any resistance and it is better if pumped several times before application. Got me stumped!