Small engine trouble

If the cylinder isn't banged up it'll be fine.
Being a small engine I don't think I would even bother trying to clean up the top of that piston.
I would pay attention where this spot is damaged though, as it looks like the screw got into the compression ring area a bit.

Great eye! I tell you what.....I wouldn't even be afraid to clean that up real good, file any sharp edges off and fill it in with JB Weld. Not like it's goin anywhere and all you need is a flat surface for the gasket to seal on.