From what I understand of the situation I'd also be looking for a better part.
If it absolutely had to be reused I'd probably turn the old threads off, weld to build up the diameter, and turn true and cut new threads back to stock size.
I'd feel better about a new part than I would the repair.

•1951 GMC 250 in the Project Journals
•1948 Chevrolet 6400 - Detroit Diesel 4-53T - Roadranger 10 speed overdrive - 4 wheel disc brakes
•1952 Chevrolet 3800 pickup
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"First, get a clear notion of what you desire to accomplish, and then in all probability you will succeed in doing it..." -Henry Maudslay-