You make my point. What he’d can you fit to the 408 that you can’t fit to the 408?? Even the W2 is undersized for 383 inches.
If you could get into some W9’s or similar you might get ahead of the 383, but I know that the W7 head was developed from the W5 for 350-370 inch engines. At that time I think they were in the 8700-8800 RPM range. That was with a single 4.
So taking that head over 400 inches and it will start to lose VE right quick unless the cam timing is adjusted. And you will hit a point where you really gain nothing up top an you just kill the middle.
That’s the issue. I like to consider the cross section and when you do, you see how limited the induction we have to deal with is.
Even for street, street/strip, strip/street stuff.