Question: Changing to front disc brakes
I used a Raybestos MC36426 from Rockauto.com 5% discount if you write this in the "how did you hear about us" box: 63216824387085 . It's $68 list, but is new and not a rebuild.
I also used one of these distribution blocks in my A-body, and it has been good so far. I haven't done an extreme brake test yet, but around here, I'm sure I'll have occasion to soon.
http://www.inlinetube.com/Prop Valves/VML104.htm