I guess that compression tester was endorsed by the League of Used Car Salesmen. Can you borrow a known-accurate gauge from a friend? If true, your readings are astounding -- I would leave that engine alone and run it another 300,000. But it does sound too good to be true.
A guy's machine shop should not be too far away, as you'll be over there a lot during the process. PO Machine is good, but if it were in Cottonwood, I would look elsewhere, too. You only stated you were in AZ, and that covers a lot of territory.
A PHX area location might be your best bet. I would get in touch with Rich Swick, president of the Arizona Chapter of Inliners International, an organization dedicated to building inline engines. [I was a member from 2004 - 2008 until the economic crash caused me to drop non-essential clubs and subscriptions. At that time there was no local chapter.] I went up to Glendale this October and showed my grubby '68 C/10 with strong-running 292 L6 in a local car show they participated in. Nice guys, but I saw a lot of Fords, and few Chevys... However Rich might have a better idea of good machinists in your area. Here's his email:
Rich_AZInliners@outlook.com
Hope this helps.