If originality isn't your highest priority, but reliability is, a 6v alternator will bring your charging system up-to-date and keep your battery fully charged. A hot battery, even at idle, does wonders for your headlights. ?
Here is the vendor I used for my 6v alternator, been very pleased with performance, price and support. This is a one-wire alternator, your ancient and trouble-prone regulator is eliminated.
Howard Enterprises
While you are at it, install new properly sized battery cables so you can get the full potential (pun?) out of your system.
(My wiring as been converted to neg ground.)