Hi Bushie, the bore looks reasonable and usable. The marks in it dont go up and down but rather laterally so thats a good sign of the piston not scraping. You will need to remove the manifold as well to look into the bore to see the exhaust side but the piston won't drop down low enough to see the upper part of the bore. With the pison at TDC you can see the lower part of the exhaust side of the bore but the window is very small.
If the piston and rings look good from the exhaust side and the motor runs fine then it would be a "fair" assumption that the bore is in reasonable shape also.
There is no muffler gasket/seal.
Powertorques are far easier to do a minor rebuild on than full cranks. If you want some peace of mind, a piston and ring kit is cheap enough or even just slip in a new set of rings if the piston is in good shape.
Keep us posted on your progress.
