I have checked a couple and one was just under 9.3 while the other was just over 9.4,this was with a deck bridge,cc'd heads,stock gaskets ect.The one thats really scary are the later 340s!.
When I take mine apart someday, I'll do a piston depth on it. It's the original 1968 std bore pistons in it, but I've had the heads cleaned up surface cut a couple of times. And I've sanding scrolled the cambers.