RE: Always a latecomer, I have need for rebuild help
My favorite tool in the shop is a dremel with the 2" fiberglass cutting wheels. It gives me better control at removing metal in tight confines. An assessory would be the right angle gear drive for the dremel which also helps get into areas hard to reach. I use a crock pot with antifreeze in it to clean engines, does a good job and makes most look like new. If your going to do a lot of this, a small lathe would be really handy. I forget the name at the moment but there is a guy that makes custom rings for a reasonable price. Someone else will probably reply with his name. I also use a sonic bath to clean carbs with. I use water and dawn dish soap for cleaning, easier to dispose of. Without that, I had to use B12 spray carb cleaner. Pretty nasty stuff but it does a good job. I would suggest gloves and safety glasses while using it. You have to make some kind of small flywheel/prophub to fit the magnet for the ignition. Thats where the lathe come in. And most crank shafts have a conical cone with a key that the flywheels fit on. I would think you have to get that perfect. I've not had to do that yet. I dont normally replace rings or pistons or even hone the cylinder. I dont get a LOT of power out of them, but enough to do a decent job of flying.
Edwin