Just one thing to keep in mind when you shim the rocker shaft. The rocker stands that are cast into the heads are machined for the size of the shaft. when you put that .40 shim in there it increases the shaft diameter to a larger size and puts stress on the outer tops of the rocker stands. This sometimes splits the stands giving shim the room it needs and also scraping the head.
it's ok to butt heads, just don't do it with a butthead
