Back to the subject of 500hp 318's? Unless you're running a stocker or a ci limited class why would you attempt it? 500hp is easy with a 360 block, a 4" crank, decent heads and a easy to live with cam. IMO it would be an all around more fun package to drive too. Plus in the long run it would probably be easier on the pocket book.
I do like to watch high hp short stroke small blocks run but have no interest to build one.