How does cid make power?

When I build a 400 into a 512, I'm not gonna keep the 7 1/2 to one, .420 lift cam, 906 heads, and log exhaust. I'm gonna use parts to match the 512 displacement, and expect a LOT more than 2%. I would expect more than a horse per inch of increase.

Wouldn't you figure if you built the 400 like your gonna with the 512 you'd get similar hp?