If you are using the wrong type of hone, method or technique it will often give you cylinders with irregular shapes.
Even a small amount of irregular shape can cause a poor ring seal / ring flutter.
Imagine what the ring is doing at 7500 rpm.
Its traveling 33060" or 2755' per minute or 46 feet per second.
You did not state how much time is on this engine. It is not uncommon to encounter excessive wear at the top of the piston ring travel. This is the point of highest temp., highest ring pressure, fuel wash down and carbon. A well worn engine will show a ridge, it should not be easily seen or felt in a competitive engine, but in a worn out car engine you can catch your nails on it.
PD: No way to fix it with a "ball hone" but you could with, say, a Sunnen hone. I would rather use an EZ Bore or other fixed boring device, but I know of several people who will go oversize using a sunnen.