Looks like a hand hacksaw job; angry ex or soon to be ex?

Whatever the case, that's a hell of nice parts car. I think your best bet would be to rebarrel it, soldering on the sights, lug, loop and foresight just as per the original. How was the original bore?

If you want you could cut the original Nock's Form off, bore it out and sleeve it over the new barrel to preserve the markings and profile.