JB Weld is not widely available over here, but Chemical Metal is the same. Also Araldite would be fine.
Drilling and tapping is possibly a good idea but cutting threads in poor metal might weaken it further, but if this route IS recommended by an expert it is probably best to use Ferret !!!!! cutting compound like Trefolex or Temaxol to ease the cutting, and take it easy. Happy to send you a spoonful if wanted.