On my FFR Cobra, I used a Wilwood slave which is .88 and originally tried a 3/4" Wilwood master cylinder. The clutch pedal feel was way too light and the 3/4" just barely had enough throw to disengage the clutch. I changed it to a 1" master, and the pedal feel was was much improved and the clutch disengagement could be adjusted.
A 3/4" master be correct, depending on the type of slave used but for my car the 1" was perfect.
Dynacorn 67 fastback. Dart 363, Close ratio Magnum 6 speed, 3.70 Eaton Truetrac, SorT suspension. Still in pieces.
'14 SHO with most all the bells and whistles. Stock for now.