Bob,
Sounds like everyone pretty much answered the question. Personally, if originality did not matter, I would go with a newer internal regulator style alternator. I think they are more reliable, although my 71 still has the original alternator and regulator on it after 28 years so who can say ! I will add that if you decide to get a new regulator, I would get an AC Delco one.
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Bill Koustenis
Advanced Automotive Machine
Waldorf Md