I have done hundreds with a dial indicator, a home made jig to roll everything, and checking and rechecking. Most shafts pull loads of 250k along with multiple car shafts. Never has one come back. The lathe makes cleaning the weld off easier but some time and a cut off wheel will work too. Quality and consistency of the weld is very important to the balance, I have seen slot of shafts need balanced just because of how some idiot welded them.
