Go with the aftermarket HEI such as the 'Summit SUM-8550055' ($152.95)or 'Accel ACC-52100' ($232.95) both have adjustable vacuum advance,,, something you might really want to consider for the street. Mags by design are for all out racing app's and voltage increases with RPM's ( revs that your engine will never see) another con is no vacuum advance not to mention cost. As mentioned before,,, low voltage at cranking speed does not lend itself to easy starting at times,,, also there are points to 'dwell over',,,, best of luck