What heads are you using? If you are using stock rect. port heads have them pocket ported, install 2.25" intake valves, and have the combustion chambers polished. I would set up the heads for a hydraulic roller cam and talk to one of the engine builders that post on the board about which grind to use. I would then go with a Merlin single plane intake and Holley 830 carbs. That combo should be worth close to 500 hp. Voodoo just posted some dyno numbers on his enhanced 502. I think you will be in the same ballpark with the parts I mentioned and if you already have the heads 3g is close to where you'll be. Good luck.