[Scarebird]

Originally Posted by RocktimusPryme

...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...

Because of course they do - they sell them!

Almost all GM combination valves sold are made for one car: 1971 Chevelle with front disc/rear brake. It of course does not matter whether the master is manual or power - same pressure and flow in and out.

The OEM's no doubt expended quite a bit of time dialing in bore sizes of the master/front/rear for optimum braking under most situations encountered by day to day driving, so in reality no combo or delay valve is needed.

Originally Posted by RocktimusPryme

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

I would agree with that. After much Quixotic windmill-poking trying to find an ideal OEM aluminum master for my TA I ended up with the 24mm Mopar minivan unit. This did require a bit of work to fit - too much actually.

The stock manual 1" bore works well enough; I suspect GM came to the same conclusion. Hence I used a 1974-80 GMC 1/2 manual unit: same hydraulics but far greater availability for my 71 Lemans.