Good point on the pushrods. Few years ago I swung through Charlotte and hit some NASCAR shops. Obviously the new engines they utilize are clean slate engineering, so the cam tunnel is way up in the block to shorten the pushrods. I was surprised how big they were, though, even being that short. My thought was they'd run as small a pushrod as possible to knock weight out of the valvetrain but the guide said the tradeoff for stiffness was worth it. Obvously running 9000rpm for long distance changes the requirements, but the theory stuck in my head.