With using exhaust manifolds I would doubt you will uncork much with swapping to an rpm air gap. One of the mopar techs even told me the m1 is just a air gap. with a spread bore flange, even cast by edelbrock for mopar.. Id just swap to a good intake gasket, coat them in Indian head gasket maker, and stick with the m1 since you already have one for a magnum. My 2 cents. Good luck.