Master Cylinder Suggestion

I just sent off my brake booster to have it rebuilt and thought I'd put a new master cylinder on it. It looks to be a Midland Ross unit off of an early 70's Dart. I'm upgrading my brakes to disc/bbp of of a 75 Dart. I have no idea what master cylinder I should replace the old one with.
This is a picture of an identical booster that I borrowed from another post.