I have .180 offset lifters, needed to clearance the heads without them when I first ran them years ago. Noel Manton of Manton push rods told me to try for .010 clearance at the closest point, that being a minimum. The purpose of shooting for .010 max and min clearance is so that when the pushrod whips (and it will) the pushrod touches briefly, stopping the side motion or flex and calming down the pushrod.