So as the title asks what brake master cylinder have you used with Wilwood break calipers? I have had a look at the following articles.

Car Builder Solutions, hints and tips
super 7 th heaven

Unfortunately I don't have the pedal to hand to measure so cant go with the 7th heaven approach at the moment. The break pedal has a balance bar installed and I have the following Wilwood calipers.

Frount 1.38" 35.1mm
Rear 1.00" 25.0mm

[Edited on 14/7/14 by ceebmoj]

I've got 0.625" front and 0.7" rear master cylinders with front and rear Wilwood Powerlites.

I'm also using Wilwood Powerlites, do you know the piston size on your calipers?

I believe the Powerlite pistons are 31.8mm dia