Poor Man's Rear JIG
We have guys around here that will shorten rears for 50-100 and I live in the high priced labor capital of the land.
I may be buying a fixture/jig set up to do this or having a friend with a lathe spin out the required pucks, as I have about 5-8 rears to do.
As long as they use a jig properly, you should be fine.