Let me clarify that I didn't doubt that you read that in a Mopar manual, what I should have said that I jhave never seen a production 383, from 1959 to 1971, that had the stock OEM piston tops above the decks You need to remember that the original beaded steel head gaskest where .022 thick and had a smaller bore size than the later 440/400 bore size .017 thick beaded steel head gaskets
Which leads me to say do not believe every thing you see in print Have you heard the old adage to not believe any thing you hear and only half of what you see
Many myths out there. Mopar, Chevy and Ford provided many false specs. to NHRA, NASCAR and other sanctioning racing organizations on many different parts they made for racing only that where not used on production cars