Maybe an internal sleeve type repair would work?

Close fitting thin wall aluminum or brass tube JB welded in place. Match the broken off external 'neck' piece to the body, clamp in place. Dremel grind off the excess JB Weld after it sets. Or, if you are careful, there won't be anything but a small fillet left fairing the sleeve in place. There'll be no heat involved with the chance of deforming the body in some way and it can be done at home.

Terry in LP