What started out as a minor engine mod/clean up is becoming major. Since we had a leak on the rear oil pan seal and wanted to replace heads and cam, we (my son and me) removed the 305 from our 86 iroc camaro. I have the heads off and am looking at the pistons. There is some residue/carbon build up at the top of each cylinder wall. How do I remove this build up safely? I was not thinking of removing all the pistons, etc.