What I did was tape the pushrod with one turn of wide masking tape. My tape is about 0.005 inches thick. I then turn the pushrod and then rotate the cam 360 degrees. The tape will tell you if you are hitting the head.

67 Coronet 500 9.610 @ 139.20 mph
67 Coronet 500 (street car) 14.82 @ 94 mph
69 GTX (clone) - build in progress......