Have you measured the distance from the seat of the outer race (on the frame) to the edge along the circle? Before going into anything irreversible, measure the distance between both seats (on the frame) of lower and upper races. Maybe your idea of putting some material under the outer race is worth to try before cutting. Cleaning, maybe scrapping the seat from some old debris, but cutting? I would be scared, especially if I don't know the reason why geometry has been changed. You mentioned crash... it is possible. Are both wheels in same line? Or has been in same line before dismantling.