There is one other possibility I forgot to mention. Water injection. There are several systems out there currently that could be made to work, it is usually recommended against as if you let it run out of water, it will detonate. Alot of the industry currently considers that technology 'dead' as they consider it unnecessary, and one more thing to go wrong. They are correct, as far as it goes. Just a thought. It will still be cammed too high for a pleasant drive, but then the car you are building should be light enough that a warmed over engine of the size you describe should make it haul. The one that's in it would make it a holy terror, if you could get used to driving it.
