[RocktimusPryme]

Originally Posted by Scarebird

We changed a 68 FB with manual drum to manual disc a few years back. Out of curiosity we left the manual drum and distribution block in. Car stopped perfectly.

Note manual masters have smaller reservoirs and MUST be monitored for fluid drop with use.

Both from personal experience and sluething in threads like this, Ive come to belive that Disc/Drum is the only setup where you might need a true combo or proportioning valve. And even then I think its a maybe. A while ago for some project or another (I think it was my 64 galaxie) I was talking to wilwood or someone about what combo valve to use if I were going to still be drum brakes all around. They recommended their disc/disc valve.

FWIW the manual master in my Firebird is the "corvette" aftermarket variety that Right Stuff sells and it still has big reservoirs with a 1" bore.

Also, from experience with that car, I think 15/16 is the sweet spot for an Fbody weight car with manual brakes.