Before going the route of the Pertronix, I switched my generator to an alternator. The main reason for the switch was not the pertronix, but the dimming headlights when coming to a stop. The generators are rated @ 20 amps / 14.5 volts. With my experience, that only happens above ~1500 rpm. Generators are not too hot @ maintaining voltage at the low rpms. That being said, I figured a good time to change was prior to upgrading the ignition system.
http://www.falconparts.com has a great way to do the generator to alternator upgrade - cheap. They sell the bracket and a one-wire conversion regulator that allows you to keep your Gen/Alt light on the dash functioning.