Same as Paul on my stock 74. Please be sure to read the link that Paul provided, especially the last couple of paragraphs about the relationship of spark plug gap to the high voltage coil. Even with the standard coil you can increase the gap to .035 and get reliable arc. I believe that this is due to an increase in dwell time with the Pertronix unit, allowing more voltage to develop in the standard coil.
Too much voltage from the sport coil just may cause more rapid deterioation of the rotor and contacts in the dizzy cap, as well