Can you even feel the scratch with a fingernail? I'd be surprised if a scratch like that would cause any difference in compression or
oil use. I'd be more concerned about getting all the rest of the glass beads out of the water jacket and wherever else they might turn up. There are a lot of much more knowledgeable people here than I, but unless someone who's really an expert told me to tear it apart, I'd be inclined to use it the way it is.
Just my $.02
Good luck.
Lowell