I know quite a few of those pistons for this stuff had positive deck heights.
To get much compression ratio out of these pigs with OEM heads you must be deck positive.
I’m out .050ish on my junk and that got me a measly 12:1 although I could get more out of it if I had to.
So to your point, it probably won’t have the compression you need if the piston isn’t out of the hole. You’d be correct that a positive deck is a big deal.