I do not know what all 68/69 engines are, but my 1969 H code 383 4Bbl a/c engine(330HP) has pistons that are above the deck surface, That is a fact, I just changed heads, Now I wish I had measured how much above the deck.
So as far as buying miss info as truth, the Chrysler guys had a hand to do with that because they built my engine with Positive deck height AND they printed info about it in books.

I can only speak for my engine, but there are a ton of cases of people having the valve kiss the top of the piston using camshafts, that are not all that crazy, by most engine standards, I was just trying to help some one avoid a costly mistake, as I will limit my cam choices to the Magnum/Roadrunner cam .(I also used the steel shim Mopar head gasket, and at Mancini's price I got three sets,its nice to have stuff on hand,just in case)

I did post the one photo where you can see the piston sticking above the block.

But I am gonna guess most 383 engines are not using the stock factory pistons anymore like my engine, so it may not even be an issue to most guys. As most new pistons have valve pockets in them as to make valve to piston clearance exceptable.