I decided to redo my top end as taking my exhaust off I noticed my power valve had alot of built up carbon. After popping off the head I notice it and the piston had alot of bad pits. The sleeve itself is actually really good with only one small spot near the bottom that has a nick. My bottom end is good with no play so I don't want to touch that. I'm wondering what can be done to the head to fix it? The damage is only on the outer part of the head as you can see. Thoughts?