Read something awhile back, I think it was Joe Mondelo. You want no more lift than 15% of your bore diameter. My 511 has a bore of 4.375 and my lift with a 1.65 rocker puts it over 15% of the bore. My measured lift is .665 . The 15% rule would be .656. The optimal target is 12%, but not over 15%. I’m thinking with my victor head(which I think suffers from lack of enough velocity) may benefit with a 1.55 rocker instead. A 1.55 gives me .625 measured lift. Just a thought.