OT: removing spun bearing material from crank

A friend rents a house on a farm and we ride dirt bikes on the parts they don't plant. There is an old JD 2750 tractor there that the owner will let us bush hog the grass if we get it running. OK, it is locked up and won't break free so off comes the head and the oil pan. A rod bearing spun ion the crank, leaving melted rod bearing on the crank journal. We want to try to shade this thing back together without having to pull the crank out (major hassle on a tractor). My thinking is using some kind of acid to eat away the bearing material and polishing the rod journal as best we can and putting in a new bearing and rebuilt rod.

Any suggestions what to use to dissolve away the bearing material that is welded to the crank?