Disc brake conversion master cylinder question.

That master cylinder will give you a high, hard pedal with those brakes. It will work and some people do like that pedal feel, but I’m not one of them. I run 15/16” master cylinders on my manual disk/drum cars, and I also run the larger 11” rear drums. The 15/16” master cylinder gives a slightly softer pedal with a little more travel. It makes it easier to feel the friction point on the brakes and makes things a little easier on your leg too.