Jason,
Obviously need to see it, but here's some thoughts anyway.... Are the threads on the horn internal (female) or external (male)? Are the stripped threads on the horn or the tip? The answers may limit the alternatives.
A couple of possible fixes come to mind....
If the stripped threads are internal, install a HeliCoil? Certainly not PC, but would be effective.
If the stripped threads are external, cut them off flush with the horn or tip shoulder, then drill and tap for same thread size. Buy a brass fitting "nipple" (a hollow tube that is threaded full length on the outside) or make one of horn and screw it in.
-Ron