When you buy your rearsets, take'em to a machine shop and they'll CNC some adapters in no time. Oh, bring your bike too, so whoever's doing it can see exactly where they will go, ya know, for clearance and all. One other thing just google "rearsets" and look for a company that actually makes them. maybe they can make you some adapters.
* You could always use bailing wire and duct tape.