A guy brought a 4.7 block in here (it dropped a valve seat) and the bore is scored in one cylinder. He wants me to bore/hone it out .020" (or whenever it cleans up) so he can put in new pistons. The block is in such good shape after 180,000 miles it got me to wondering if these bores were Nikasil. I guess if we bore it we will be down to regular cast iron? Any helpful hints? Thanks