[yossarian19]

Originally Posted by CharlieSheen

I just wanted to really thank everyone who helped in this thread,tons of great information here.

As this thread is a couple years old...Any of you guys have any follow-ups on how everything is working,as you put on the miles?Anyone make any changes or modifications to their original setups?

I'm running the pedal assembly sold by Speedway Motors and I mounted my Astro Van hydro boost to it. I'm using an Astro MC, too, but I had to switch to an S10 reservoir for clearance to the cab floor. Owing to the length between my PS pump and the HB unit, I had custom lines made ($35, hydraulic shop) and they could fit better length wise but they work.
I think a 70s C10 master cylinder with the integrated iron reservoir would fit better for under-cab clearance but I haven't verified this. It's my only kvetch in a system that seems to work damned well.
The 6 lug front disc swap I bought uses 12" rotors & GM "large" calipers. The rears are factory '57 drums. This closely mirrors the Astro Van's brake caliper / MC / wheel cylinder sizes and it works. Pedal feel is good, stopping is excellent.
Not to ramble on too long, here, but I sized things relative to each other using factory brake systems as a guideline. The closer you can match an OEM setup the better. There's some wiggle room in the MC selection but not a ton - and I believe Chevy's engineers knew what they were doing most of the time. Any case, the Astro junk works nicely with 1" wheel cylinders and GM "large" calipers.