header flanges are the same but they ports on the heads are raised about 3/8 of an inch so not in the stock location.

The intake valve is moved and you need special rocker arms that are .800 offset.

The 440-1 flow about 80cfm out of the box better than those heads and are capable out flowing them big time with fully ported.

They are in a different league, big step up from Procomp/Eddies.