How much should a basic 340 rebuild cost?

Why? I have a real machine shop I use. NAPA would be down at the bottom of the list.
When you mentioned that NAPA by you still did machine work. I don't know how they are now but I know that at one time they did great work at least the one that we used. As far as a quality machine shop where I live would be about 25 miles away, they do good work and are reasonable