Daryl and other 12A owners:
Poke around on the f3csclub forum. It's been some time since I was on there. But, there was some rotary guru (lightplane rotary enthusiast IIRC) that was resurfacing rotor housings.
There was a long thread and a link over there (I can't find it now) about how he had tried different materials and application processes. Came up with something similar to a ceramic JETHOT type coating, he builds the material up a few thousandths and then machines it down in several steps. YES he made some machine/fixture/jig/CAD-CAM process (top secret) where he could machine them back down to original spec. He was experimenting with different surface properties (some held too much oil/fuel, some not enough) Lots of close up pictures of the housings after each stage in the process.
Granted, as the rule stands now, this may not be permitted. But perhaps a provision needs to be made to allow sleeving of blocks and resurfacing of rotor housings.
A proposal along these lines may have more of a chance of being accepted than an alternate housing that wasn't imported in to North America.
Good luck!
Daryl DeArman