As I just recently went thru this while upgrading my SPF brakes.
Check the pedal ratio first!
For a manual system is should be a minimum of 6:1 but 7:1 is better.
A = Distance form pivot point to middle of push / pull point
B = Distance form pivot to point of push on master cylinder
P = Pivot point
F = Force or push
Once you get the ratio correct you can tailor the M/C bore size to provide the suitable line pressure.
Jason