Destroked Small Block?

The way I look at displacement is static and dynamic. Static is what it is measured out non running eg. 340 360 440 etc....
Once running the displacement is basically dynamic. A 360 vs 402 becomes (cid x rpm)÷ 2 but that number is meaningless.

Cfm is something more relatable.

So that carb formula can be used.

(Cid x rpm) ÷ 3456 = cfm

402@6000 = 698 cfm
360@6700 = 698 cfm

You can see both are able to pass the same amount air/fuel and have the same potential hp at those rpms.

Or an easier way to calculate. Since it doesn't really matter the cubic feet or inches per minute.

You can do it this way (cid A x rpm) ÷ cid B = comparable rpm, 402 x 6000 ÷ 360 = 6700