Thanks for all the tips. Here's how things went. While searching my toolbox for small masonry bits to enlarge the perimeter I found a couple mounted stones with 1/2" shank for a drill. They were 1.25" diameter with a nice conical point to guide into existing hole. Once I removed the existing tubing it only took a few minutes to enlarge the hole on each side of the block.
I found it interesting that the propane "professional(s)" that originally installed the regulator used pipe dope on the copper flare fitting.
I found it interesting that the propane "professional(s)" that originally installed the regulator used pipe dope on the copper flare fitting.