Good food for thought Tiny. I've been doing some more research via the WWW and theres a fellow that modifys the 6v & 12v gen housings to hold either a 6v or 12v alternator. It looks like a gen but is really an alternator. I also found a source for a std 6v alternator.
In thinking further, at this point the only "need" I'd have to go to 12v would be to power a sound system. But until I do some body work and add beau-coup sound insulation I wouldn;t be able to hear one anyways

DavidF. great idea on using a relay to control a "switched" power buss. I also like the reasoning for a 3 wire alternator.
Great input.
Dave