Big Block Cylinder Heads "915 vs 906"

Everything depends on the application.

If you're building a 'restoration car' or 'general street performer', you can
make a set of 'stock' #915 or #906 Heads work fine, with a little massaging.

If you have an 'extra $1500, a set of Edelbrock Performer RPM's will do the trick.

With some 'nifty' Seat Angles, and just minor porting and bowl area smoothing,
the 'stock' Cylinder Heads work fine on the street.

We've got a customer with a 440 in a Duster, that runs 10.30's with #915 Heads
and 2.08" and 1.74" Valves, and the car on occasion, is 'Street Driven'.
He's one 'Happy Camper'.