Im in North Idaho. In researching I discovered that the Gen1 CMX250 only ran from 85-87 and then bolt patterns on the barrels changed in 88. So I have very limited pool of used parts. I am currently looking at going one of two ways, dropping a newer CMX250 motor in (parts will be easier to get ahold of) or taking a gamble on a ZongShen 250cc thumper.
The ZongShen is an interesting route, my knee jerk reaction is never buy Chinese motors, but I recently read that they are making motors for Norton and Aprilla, so thats something right? I can pick up a brand new motor for about $350 USD, might as well buy two for the spare parts. Run the thumper for a year or two until my wife is comfertable and ready for something a little bigger. Then either take the time to do a full and proper rebuild on the original motor and fully resto the Rebel, or turn it into a little bobber and then who cares what motor is in it.