A bigger master cylinder bore will move more fluid so the pedal stroke will be shorter. It will also require more pedal effort to get the same braking effect because the line pressure exerted by the bigger piston will be less, not more than the smaller one develops.
Residual valves on drum brake wheel cylinders keep a little pressure against the tapered wheel cylinder cups to prevent air from being sucked past the cups as the master cylinder retracts. Since the brake shoes are spring-returned there will not be any drag on the drums even with 10 PSI residual valves. Disc brakes with that much residual pressure would drag all the time and overheat. 2 PSI residual pressure for discs, 10 PSI for drums, regardless of the position of the master cylinder.
Jerry
