Not saying a 416 vs a 360 can't squeeze more power out, "I just have no theory how it would" ?, to me torque is a factor of CR, chamber shape, VE%, displacement etc... Torque is a snap shot of one power stoke which defiantly tied to displacement and efficient. HP is all the power strokes added up. I'm guessing it would have something to do with port velocity and size that these 302 ish cids can't use up the cfm's. Cause I find cam size don't very a lot when it comes to serious street/strip 230 to 250 engines, 400hp, 500hp, 600hp only mainly difference with heads ability. How would you build a 500 hp 318-328 vs a 500 hp 408-416 ? Obviously you stated the 302-318 side but what would be the difference for the 408/416?
The only thing why I can think of why some small displacement can't scale up in hp as larger displacement engines sometimes, is it's become harder as rpm rises.
