440 factory heads foodchain....
As I understand it, that's what the "experts" are saying.
Jim I'm not looking for a pissing match , but look at all the aftermarket performance heads , the ONLY open chamber head is one version of the Ebrock RPM , everything else is closed chamber.
If someone is STUCK using stock Iron heads they all have their good and bad points. For my builds I have to use 906's because of class rules , for stock untouched there is one casting that flows a little better than the others , but once you port them they are all the same , core shift being the great equalizer. as far as the later open chambers , the 452 intake port has less short turn so it's EASIER to port , and I think fast68plymouth said it had a better exh port as cast ...
I just worked on a set of Paul Rossi street fighters that I bought in 1989 which is the 452 police motorhome head .. it has the 5/8 taper seat plug and the extra cooling passages around the plugs ... , one was an NOS casting , the core shift on these heads was the worst I've seen on all the stock iron junk I've had to work with .