Manual disc brakes vs power disc brakes questions
The rule of thumb is increasing to a larger bore master, while leaving the calipers a stock diameter = harder pedal, and decreased clamping force at the wheels.
Using a smaller bore masterwhile leaving the calipers a stock diameter= softer pedal and increased clamping force at the wheels.
I am going to use a 1&1/32" bore master which is stock bore for A body manual disc brakes, however i increased my caliper piston size from 2.60" to 2.75" using cordoba big brakes. Instead of making the master cylinder bore smaller, i increased the bore size of the calipers effectively accomplishing the same thing. I will see how this goes, and may decrease the master bore size in the future if i feel the pedal is too hard.
As a side note dippy M body calipers use the larger 2.75" diameter pistons, and the rotors and brake pads they use are the same part numbers as an A body.
15/16" bore master cylinder can be found by speccing out a mid 70s A body with power disc brakes.