soft brake pedal

actually 4 1 5/8 pistons in a kelsey caliper are 8 sq inches where the larger single piston caliper at 2 3/4 is only 6 sq in.I have a 1" master in the Duster with the 2 3/4 piston caliper and there is a bit of travel for a rock hard pedal, but for normal driving the brakes stop quickly long before the pedal ever gets hard....very nice.
i do think i need at least 1" master for these kelsey discs and may be why i am pumping twice to raise the pedal initially...and i have since found some seepage ..

When you measure caliper piston size, for whatever reason, you only measure one side on a four piston caliper so it's really only around 3". Using the SSBC calipers I have on my car as an example, piston area comes out to a whopping 2.94 square inches. Awesome.

15/16 master cylinder is the right size for the KH brakes. You'll have to live with a little longer pedal stroke but the pressure will be correct for the application.