Anyone use these for over 500 lift cam

I've seen something very similar to these used on heads using longer t/a or W2 length valves with .650"+ valve lift on the intake.

I wouldn't think they'd be necessary for sub .550" of lift

For people like me who put longer valves in it works well. The 318 valves I put in the slant head were long enough that they moved far enough away from the rocker shaft, correction was needed to get geometry right again. His shims got it dead right.