Has any one ran a Alternator with a internal voltage regulator?

Don't discount the possibility of the ignition switch being bad. Over the years the contacts in the switch tend to wear or get dirty. This causes a varying voltage at the ignition terminal of the voltage regulator. A lot of times you will notice that your headlights will have a flicker to them. I fixed this condition by adding a external relay. I fed the relay coil off of the original voltage regulator wire and supplied the ignition .terminal of the regulator from the normally open contact of the relay that was being fed from the hot post of the starter relay. Just something to think about.