Head gasket replacement presents new dilemma?

I have never had a problem with the old reliable fel-pro set. Was that plug wire from the problem cylinder? If so I think you found the culprit. I agree, antifreeze will steam clean the combustion chamber real good. Look at both 6 & 8, they are much cleaner than the other two. Also note that 2 & 4 exhaust valves are a different color.