re: Piston-to-head: what's ideal? What's safe?
Speaking of Jim Moore; based on his experience with 4.25 stroke combo's, I chose to run my 540's quench @ .034" (.007" ITH + .027" MLS). My clearances are .0033-.0035 mains (little big but chasing a bearing issue), .0025 rods, Scat 6-weight crank, Scat H-beam rods and Mahle Power Pack 4032 pistons w/Line-to-Line coating. It runs 7500 rpm's thru the lights and has accidentally spun to 8000 (rev limiter) a few times. I think if it was going to touch, it'd happened by now. YRMV
Not meaning to change the topic here, but with those 4032 alloy pistons you have in there, do you ever notice piston knock when the engine is cold? My Mahle coated pistons are the 2618 alloy, and I never had the 4032 stuff.
70 Chevelle SS clone (632 CI powered).