There are a couple of counselor articles addressing different heads and compression ratios. They are earlier articles but applicable to all the later S8s--except maybe the 359. Check outhttps://www.packardinfo.com/xoops/html/downloads/SC/SC-VOL24NO7.pdf andhttps://www.packardinfo.com/xoops/html/downloads/SC/SC-VOL25NO4.pdf for starters. I believe there is another later one or at least a book article more to your specific question and how heads were marked. Can't think of which or where it is right now. Believe the STD stood for standard trans and the 327 indicated the optional ratio for that engine but don't remember the exact combination.
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