Going "waaaaaay back" in history here, but the data is still valid IMO.

Had stock rebuilt 440 w/ unported 906 heads, a 222 @ .050" x .455" hydraulic cam, stock converter, 3.55 gears, 1-3/4" headers, etc. With sticky street tires it ran a best of 13.2 @ 103 MPH.

Picked up a set of '452' castings machined for 2.14" / 1.81" valves. I did a fairly extensive home porting job on them w/ some touch-ups done by a local cylinder head shop. Swapped heads, along with switching from OEM stamped 1.5 rockers to Crane 1.6 iron rockers.

With no other changes, the first time I went back to the track the car ran a 12.5 @ 109 MPH, although the weather was awesome and the car dropped off a bit from that under more average conditions. Still, that means the head porting and increased rocker ratio for the small cam picked up 40-50 HP.

As suggested above, I'd be looking at set of "prepped" Sidewinder heads to get some serious CFM improvements in the <= .500" lift range.

"Your results may vary!"