In your post about the reed valve mod, I think that the transfer port size is holding u back. On the newer jug, the ports are very narrow. On my jug, i removed the metal between them completely. I have not been able to test the mod yet (its just too dam cold here in canada) I have been told that the mod might cause problems with the rings not being properly supported. As soon as i can get this engine running, i will post a video. The only other mods to my engine are bigger carb, modified muffler (just drilled two 1/2" holes) exhaust changed to approx 150 degrees, and the transfer port mod.
To stuff the case, if you were to machine a new backplate, you could have a recessed area that would clear the conrod and crank pin. Just be careful when stuffing. I blew up a homlite 25 doing that. the plate that i used was too close to the crank pin, and when the metal expanded, the pin gouged it and the metal pieces jammed and broke the ring. It was spinning at about 9000 rpm when it did this, so it made one hell of a bang.