I bought the 3" high lip (Golden Tee) ball from Happs (not the high ball).  I routed out 1/16" from the top of the CP and mounted the ball using the Clear Zinc mounting kit.  At that point the trackball housing was approx 1/8" above the zinc mounting kit.  Added my overaly, added my lexan, and wa-la, perfectly flush.  Not sure how the standard ball will do height wise, but this was perfect....