440 stealth heads.

They’re usually in the 260/[email protected] cfm range ootb.

Recut the seats and blend the bowls gets them into the 280/200 range.

You have to work over a stock head pretty hard to get 280 out of an intake port.

One of my customers just dynoed a 493 with a set that had a little more done to the intake ports(290cfm).
6bbl, headers, solid cam, pump gas...... 625tq/580hp.
The cam was set up for ex manifolds(that’s what will be used in the car), so there was some power left on the table.