Make sure they are adjusted properly. I drove a 63 300 with NO brakes but everything was new. We just didnt adjust them properly. You should have a rock hard pedal within about an inch or you got air in the system or a bad MC. Bad MC is more of a sinking pedal though. Smaller bore equates to more travel and higher pressure with same output, larger is smaller stroke but less mechanical advantage. Bleed again. gravity bleed if you got time, crack all four cylinders and put a cup under each drip. Keep eye on MC level over a few hours of football. That 10lb residual valve is old school, as stated it was for piston sealing, new ones have integral springs that do the same thing. Dual drum should have 2 of the same fittings, disk.drum usually have 2 sized fittings and one res larger than the other (disk one) as they displace more fluid. Oh, and of course the elusive "turned drums and new shoes that were not radiused" equates to reduced contact area.