I have the same problem I have a number in my head, but I checked the 1969 FSM just because I couldn't remember the factory number. Guess what - they do not give one. Nothing. I was shocked. So, falling back to my number, I use .0005" (half a thou) per inch of radius on the face. That would mean an 11" clutch on a 14" flywheel would have a max face runout of .007" at the edge and about .002" at about the center of the disc contact area (roughly 4.25" out from center). Of course, this would change with clutch disc diameter and flywheel diameter, and is only the number I use from wherever I got it. I've also heard (don't remember where) .002" runout anywhere on the disc contact face to avoid chatter.