head decks, and still not flat, you may want to show son how to measure compression ratio/cyl and adj heads for something that will run on regular gas. Depending on cam and spark advance curve, 9:1 should be fine. I would not use valve springs with that much variation or less compression than spec on a fresh engine rebuild. Newer materials should be better and within a % or 2 @ 120K miles. You never did get back with the new stock piston/bore clearance w/compression rings end gap measurements between top and bottom of cylinders. However I won't try to limit your freedom of how long an engine you are trying to rebuild lasts. Maybe car is named Sloppy Floppy and just fine down on the farm running local errands.