I've been posting concurrently in the main XL600 thread about my engine's top end. For the sake of the continuity of this thread I will recap.
I bought, on eBay, a re-bored cylinder and Wiseco 101mm piston.
I posted in the XL600 thread some concern I had about possible downsides to using a "high compression" piston (Wiseco claims 11:1, but most folks on here are saying this piston is 10.5:1, tops). However, the consensus seems to be "go ahead and use it", even with the stock cam. So that's what I will do.
I'm pretty sure I am going to change up the color scheme of the engine a little... black bottom end, bare metal cylinder and head, and black valve cover. I've already sand-blasted the head. I'll blast this newly bored cylinder soon, then install it.
Here are pics of the bore and cylinder which are the ones I will be replacing. Even though they are clean and good looking, I figure that if I can use the 101mm Wiseco and the stock cam with no pinging, then I might as well.
OK, that's all for now I guess.