I finished grinding on the 440 source heads that I'm putting on a customers 383 bracket motor, they have a set of Crane 1.6 ratio ductile iron rockers and 3/8 pushrods. Picture one is of #4 intake port wall, some of them required more grinding than other ones All of the intake rockers required shimmimg away from the stock rocker shaft holdowns My message is make sure your pushrods clear all the way down, at closed and opened