I have to agree with the above post. Bore it a little and use slightly larger matching pistons. .030 over wouldn't hurt it and then you'll have a good fresh surface for the rings to seat against. You can also get the rotating assembly balanced as well. Both will help reliability and performance.
More wrench time. I enjoyed helping a friend wrench on his door-slammer. He offered to let me drive, but I really prefer wrenching and this has continued on into my RC racing.
Hope there is enough time at the test and tune for a little "smoke show" video. I used to help wrench on a friend's door-slammer when he'd race at Heartland Park in Topeka. It's a lot of fun even if you're "Only" wrenching...