I already have a new master. I believe it is 1 1/32"...the one called for in the books. But, I can always save it for another project! I have installed a proportioning valve, but didn't know about the 7/8" cylinders...good tip. Thanx.
With that big bore you will need two feet pushing as hard as you can on that brake pedal just for normal stopping. It won't be fun. Those KH brakes in stock form are pretty crappy that is why you need the 15/16" master cylinder, 7/8" rear wheel cylinder, and proportioning valve. I run the Red EBC front pads too. Once I got all the brake mods in place the braking is really good with minimum leg effort. Here is the write up I put up on my web site:
The same KH front disc brake system was used on the first gen Mustangs; different rotors but same calipers and same brake pads as a-body mopars. Surf around those first gen Mustang sites and you hear the same complaints about weak poor performing disc brakes.