How does cid make power?

You tell me? How can an engine that has peak power at 6k have the same curves as an engine that has the same peak power but at 8k?
You post says shift point of 6k and 8k. I'm not a drag racer but don't you shift at some rpm past peak usually? That part doesn't matter. You're saying now that the motors make the same power only at peak for each motor 6k and 8k? Wouldn't the rest of the curve matter as to how the car performs?