Power to manual brakes

Very few if any drum systems need a prop valve. Are you keeping drums or converting to front disk?

My car (when it was together) had 4x disc brakes, 73/74 Duster/ Demon in front and Linc. Versailles at rear

So far as master you need a different length pushrod and usually a smaller master which gives you more leverage but requires more pedal MOVEment

Dr Diff gets great press on here, I have not dealt with them