I would take some time with the toasted rim, and try to untoast it. Tom described a method where you draw a perfect circle on a perfectly flat surface, and check your rim against that. The rim has to be completely unbuilt. Find the flat spot and bend by hand (or use some scrap lumber &c) until it matches the circle and lies perfectly flat. Hammer out any dings and dents. Then build the wheel up. It's certainly worth a prolonged try!