Well, you can always follow Steve's lead...
Engine Masters, Spring 2009, the article titled "383 Power Play", using it ONLY as a GUIDE for YOUR APPLICATION). Not all mods in the article would suit your purpose, BUT the text is well defined in
hands-on tech!! As far as those big-valves
in the 516's, be cautious! Do your HOMEWORK on those heads FIRST! I'd use the tech archives and other tech article as a learning tool before the trial and error on those heads. Might find that a comp. valve job and backcut 2.08 intakes and larger 1.74 exhaust valves may work, maybe not (depends again on cam selection). Or maybe a set of 906's may fit the bill. Simple, BUT effective mods are good - exotic and expensive mods are WASTE of TIME and PERFORMANCE!! The K.I.S.S. principle.