Bingo, If you can get a diode pack for cheap then replace the diode pack at the same time, with alternators its always in for a "penny in for a pound" and the diode pack isnt far behind a failing voltage regulator.
All the overdrive pulley does is provide more amps (to be consumed) earlier on in the speed of the engine, ie, at lower rpm's.
Its equivalent to a stock alternator being a big chubby german chick giving you
one Braunschweiger sandwich (stock alternator)
vs the another big chubby german chick giving you
five to fifteen (overdrive alternator) Braunschweiger sandwiches AND a large mug of Helles Bier.
The important thing to remember about amps is, you don't necesserially /need/ to consume the extra amps, they are just there to be consumed incase you DO need them, ie running a CB radio, 100 watt flood lights, etc.
So having more amps won't necessarily overcharge a battery, but those extra
volts will
force the battery to overcharge. So replace the regulator unless the battery will be a cooked battery soon.
The last thing to go, ironically, is the stator brushes (aka commutator).
Oh and bearings too, if you can manage to get them for cheap and get them out easily.
Otherwise just get a rebuilt one with all-new parts inside.