Make Sure That The Adjusters On The Harlan Sharp Rockers are No More Than 2 Threads Showing When Doing This Mock Up/ Geometry Check. Try A Turn Either Way, And Keep Checking Your Location/Pattern. I Have HS Rockers On My 428, With Trick Folw Heads,Set Them Up As Reccomended, Didn't Need Shims Or Cut Down Stands Or Anything. Parts Have A Way Of Stacking Tolerances, And Different Combinations Can Have Different Results. Good Luck.