Earl,
Here is a very very rare thing to behold. A WORN OUT FOX!
NO amount of re-ringing or even honing on my part can bring this sleeve back to serviceable condition.

Note that because Fox pins the ring to the piston it did not rotate in the cylinder.
This allowed the ring to wear in one spot causing what looks like a bump where the ring gap was.
The wear under the yellow line is 0.0022" in diameter. All but 0.0002" of that is on one side under the ring gap!
I would have to hone the cylinder close to 0.004" oversize just to clean up this wear.
I'm pretty sure that at that size I would break through all the nitrated steel and be well into the soft leaded carbon steel.

All the rest looks good. Of course it would it is a FOX! The Fox is a great sport engine with a nod to being more!

This engine was run for 4 years on none castor oil fuel with 5% nitro. The brand name was a local brand called BK hobbies.
While the guy who owned the engine did use ATF as an ARO I was surprised at how little rust I found in the engine. and this was after 4 years of hard running with about 120 oz of fuel run through it every week all year long. I can attest to the fact that the engine was run hard and at times lean! It still ran good, but not as good as new. It just needed an electric starter to start reliably.

This is the engine I parted out for your Eagle II upper cylinder casting.

All the best,
Konrad