Was the frame shipped to you. More importantly, was it shipped to without a block or one of those plastic things to hold the drop outs in place. If that's the case, I'd have to say it was a 120 that was squoze in transit. I'd probably just try putting a normal 120 track wheel or even just the hub in there without trying to correct the spacing. Actually first I'd lay a straight edge along the seat stays to see if one or the other or both show a bend at the bridge. If only one looks bent, I'd call a frame builder or repairer. I would not try to repair it at home.