In Morton, IL we were pulling the 273 to 8,000 rpm on that dyno. Maybe it was only 460+ horsepower, I cannot remember, it was like a billion years ago. The engine belonged to a Chenoweth customer so to protect the engine we pulled out. In retrospect, the engine was sound enough we could have fired the engine, made the three qualifying pulls without shutting the engine down and kept going with the three scored pulls and won the contest.
Here is another description of the contest by Mopar Muscle....
Looks like MRL built a 470hp 340 that used unported RHS x-heads and he used a solid flat tappet cam while all the other seem to have solid rollers.
Was porting allowed on the heads in that competition?
Yes porting was allowed. Chenoweth built the shortblock and we did the cylinder heads. Those heads, when repaired and touched up, went onto a 360/424 stroker that eventually made 629 HP on 91 octane pump gas. We had four of those heads and the same exhaust port was thin in the same spot. I think it was the #2-7 exhaust port.