How much should a basic 340 rebuild cost?

I'll tell you one thing as a small shop engine machinist.
Be thankful anyone wants to be a engine machinist.
As an engine machinist I can verify, it is a very underappreciated and underpaid job.
If I had to pay for any of my machine work with my wages I wouldn't be able to afford it.
I don't use the shop enough to call it a benefit either.