Well I want some other people too chime in on an idea I have for brakes on my Caprice

[MonzaRacer]

So I found the master cyl leaking so I have a spare Monza Master cylinder, Factory size is 7/8.
I found out the oem master is 1 in, but the oem master cyl for metallic shoes is 7/8.
So I was wondering if I were too swap in the 7/8 dual master cylinder if I would have any issues other than possibly more touchy brakes, which I CAN learn to modulate.
My intention is to add in Disc brakes in front next year, and possibly rear disc later on.
I am just wanting to NOT buy a single master cyl and really dont like the factory 65-70 style disc set up, I was informed about using C3 spindles and such but kind of was looking into adapting on C5/C6 type calipers.
If master cylinder didnt go bad on shelf (took it off wrecked Monza few years back) and it was reman when I got the car going.
So anyone have opinions, ideas, cautions.
Car is , right now, 4 drum manual brakes, great pedal but I just found out master cylinder is leaking.
Been debating an adjustable brake prop valve, just wondering if I really need it on a dual line set up.
Thanks.