Replacing single reservoir M/C with dual reservoir on four wheel drum system

I used a manual disc brake master cylinder when I did the upgrade on my 64 Valiant, Vixen. I have rebuilt Kelsey Hayes discs for the front, but have not installed them yet. The car stops great and does not prematurely lock the brakes like everybody always says. I only wanted to do the master cylinder swap once, so I went ahead and installed the disc brake unit and it works fine. I still have yet to install the disc brakes ans it still works great.