need help with big block heads

[3kidsnotime]

The SD catalog you quoted is not all that correct as well the only 6 block with a fuel pump boss is the over the counter replacement service block that is why the water passages are smaller and fuel pump boss added gm made a block to sevice all the engines with that one. The production gen 5 and 6 454 vortech engines in trucks from 1991 to today in the 8.1 have not had a fuel pump boss the only ones I have with them are service replacements. the aftermarket industry has made added deck surface to the heads with a small water passage to fit 4 5 6 blocks the new gen alum heads from gm performance are just Edelbrocks with gmperformace on them. Good question who is the largest purchaser of engines from GM I might post that its a good question