I have a Comp Cams Extreme Energy 268 in my 340. About 12 years ago, Mopar Muscle magazine took a stock 340, threw a bunch of parts at it, and if hit 392 HP. I followed that exact recipe, but went one notch smaller (750 vs 800 CFM) on the carb. Edelbrock Air Gap, headers, Comp Cams Extreme Energy 268 cam kit (springs and all). I a SO happy with that cam. It runs great and has a very nice lope at idle.