You don't need 2 inch headers, if you need new headers I'd go with 1 3/4 inch. You don't need anything larger for a 500 hp 440 inch engine. You'll want to keep the cam fairly small and maybe spread the lobes to 112 for better vacuum signal. I'd think something in the 220 to 230 range at 050 is as big as I'd go. Hyd roller is nice but expensive. Maybe talk to Oregon Cam Grinders and see if they have something for that engine.
