I'm not sure how to address your comment other than to say that if anything
is going to give you a false reading a brake booster will. The basic
physics would suggest that if you decrease the master piston diameter you
will increase pedal travel and, for the same foot pressure, increase
hydraulic pressure resulting in higher braking forces. I had evaluated the
original cylinder against a Corvair for diameter and effective piston travel
and determined that I would be comfortable with the results (us engineers
like to do silly things like that you know). Why a Corvair you ask,
principly because I had one handy, it was meant for all drums, and the
physical interface was the same. Anyway I am very comfortable with both the
pedal travel and pressure I have and the braking effort I have.
je