proportioning valve??

Use the third one on the right of the picture at this link:

http://www.inlinetube.com/Prop Valves/BLK245.htm

It's the one for Disc/Drum and it will work with manual (no power booster), I know because it's what I'm using on my Demon with same brake set up.

For use on 1969-74 A-body Mopar with drum or disc brakes.
the blk250 is this the 1 it looks just like the 1 on the car