Found the Mag today. Yeah that Chevy has similar flows, a bit better due to the larger x section and the much larger 2.15 intake and bigger 4.155 bore probably help too. The Chevy was a dart block, a much more expensive package, even though they did it all with a hydraulic roller cam.

My 414 is very similar in all respects to the 408 so it should be fun...can't wait for spring now!!