That's my question. What is the stock deck height? I've seen them as tall as 9.620 and that was my X block. It was brand new in the box when I bought it. I have a 340 block out there that was 9.565 before I cut it, and another one that is 9.510ish and has never been cut.
When the blocks were machines at the factory, they only cut on them until they had a viable surface. They didn't machine them all down to the factory max spec or the minimum.
That's why you had some engines that ran like a scalded dog off the showroom floor and others needed to be machined first. You had tolerance stack up. You could have a tall deck, short rods and big chambers. Instead of the 10.5:1 you should have had, you'd be lucky to get 9.25:1 with all that stack up.
You have a nominal height, the max they let out the door and a minimum.