The guy i bought it from had already pulled the head. Everything, other than the rockers, looks fine. I don't want to take any chances though so I'm going to replace the whole head assembly as a unit (cam, rockers, valves, etc). There are no visible marks on the pistons though I'm sure they made contact with the valves. My machinist is inspecting the head now and will let me know the results. Even if it checks out, I'll go with a new 4D56 head assembly and sell the 4D55 stuff or keep it as a spare.