304 making 405 hp with modified 304 heads

That sorta like the 63 split window vette, that had a fuelie 327. The guy set it up to turn in the high limits. Did not get much power below 4K. The 304 has huge breathing capabilities with valve and head work for high RPM use. It has a good stroke for either turbo or supercharging, if wanting more power. For that to pan out, it would be setup more like a traco 304, just smaller bores, when competing with 5.0L class. Though the larger bore, like the boss 302, is how to get a quicker charge over the stock bore of a 304. Probably why it's dead below 3500 RPM. Bigger bore would bring in the RPM torque band a bit wider. Though you can always push the limits on a 304 over bore to some degree. Drop in a 343 crank for a shorter stroke and see how fast 8K comes in.

I never disliked the 304, but for street and occasional strip use, it takes a bit to keep up with all the bigger engines, even more so with aluminum engines being common now. Out classed by weight and electronic / hydraulic controlled timing curves. Does the mighty 304 in.

drop that one in a hole and backf fill it. 

IMO the 304 yields nothing to the Chevy 302 except weight.

Ok, so the short block is a tad heavier than the Chevy
The crank is also heavier by 10 lbs~
The crank is longer with 4.75" bore spacing vs 4.4 for the Chevy.
the 302 was internally balanced.
The oil system in the Chevy may be the best of the small block wedge head engines.
The intake valve angle is an old argument but the Chevy had a far better
short turn radius in the intake.

So I guess I may be wrong again...
But reciprocating weight and oil system along with a far better intake for
high engine speeds may be the reasons. But 50 lbs is still 50 lbs.