Just finished a similar project for my Scamp . Started with a 383-2 : 1968, 383Magnum TRW forged pistons = 335 h.p. 1976 (915) heads with larger valves and bowl work . don't spend more than $600 on heads or else get alloy set , good for 20+ h.p.. Headers : T.T.I. 1 3/4-1 7/8 " = 30h.p.. Cam : somewhere near .500 lift hydrolic flat tappet = 25 h.p.. Roller rockers = 20h.p.. 750 c.f.m. carb. =10 h.p.. Block prep. and balance = 10 h.p.. You are there with 440 h.p. and no sweat . I think the compression ratio is right on for pump gas . If you can't get premium fuel in your area you can drop the compression ratio by using a .042" head gasket . Camshaft selection is critical here . Can't go wrong with the Mopar Performance line or the ones from Comp Cams . I'm a big believer in balancing . Makes for a happy motor . You can add headers later if you are on a budget . They are expensive but they work like heck . I did mine for less than $6K U.S. not including headers . Good luck , Tom
