[Febo]

If the head gasket was super blown your engine probably wouldnt have even ran. But if it was leaking, you would get low compression and lots of oil useage. It could also just be from separating the head from the block, thats not the cleanest operation in the world. And WD-40 or just some parts cleaner and a rag will work fine to get most of that out of there, but those carbon deposits might be a tougher challange.