Hi, apologies for the late involvement.
Was just browsing for Perkins advice when I came across your post. As I understand it, the Perkins manual for a 4.108 states that there is no tolerance for skimming the head? I think I have the same/similar issue as the OP, hence looking for advice re head skimming as I was surprised to find I'm not supposed to to skim the head? Thoughts?