542,

As delivered the '337 leaves the ports very much on the small side compared to a true Max; they're more like dead 1/2 way between a standard 906 and a 2.6" x 1.3" Maxie, this may be so it could be possible to use the 337 on an 'oversized' 906.

I've actually ported several Holley street dominators with larger port windows than the 337 comes OOTB. I wasn't exactly pleased to see how much work they would take to port match my Max Wedge heads. What they do have is a very generous port entry from the plenum with good taper, I was pleased with that considering to look at it visually and it's low carb height....at first glance and it pictures it didn't "look" like much.