I always get a chuckle out the “cubes don’t matter” arguments.

If that were the case, then why is it in pretty much any racing series or class that has a cube limit........basically has the entire field running the max allowed?

Take NHRA Pro Stock.......bump the limit to 550ci.
No one that stayed at 500” would be competitive in a very short amount of time.

Having a combination be more “efficient” isn’t the same thing as making more “power”.

A 470 making 700hp is 1.489hp/ci
A 511 making 735hp is less efficient at 1.438hp/ci....... but it’s still 35hp more.

As for the 4.25 stroke/6.535 thing being some sort of hurdle to overcome........
This is one of their budget friendly combos:
https://www.shafiroff.com/chevy-drag-race-engine-sportsman/565-big-block-drag-race.php

Here’s another one....... more hp, more rpm...... same stroke and rod length:
https://www.shafiroff.com/chevy-drag-race-engine-pro/565-big-block-drag-race.ph

The rod ratio for a 6.535 rod and a 4.25 stroke is 1.53....... same as a stock 454 or 502 Chevy.

Shafiroff also sells a 440” small block with a 6.00 rod and a 4.00 crank, which has a slightly poorer rod ratio of 1.50...... that one makes 950hp.
Peak tq @6800....... peak hp @8100.