911 Alt wiring help !

[Wally]

You need an external regulator by the looks of it. I have only wired up Mototola's, but it looks very much the same
Be sure to get the matching regulator! There really are a lot of differences in voltages and currents. Only a specialist that has a book with all the numbers can help you there.
The two B+ leads are there to be able to choose which one is more suitably located for your wire set-up, so I was told. D+ is where you hook up the charging ligth, just like in your bug (blue wire of the bug).
D- (brown), D+ (red) and DF (green) are needed to go to the regulator. These wires probably are already in your bug, as 1974 was the only year with an external regulator !
Good luck.
Walter

Disclaimer:
I take no responsibility for any mistakes in the above directions, which are just meant as a suggestion.
(sorry for this, but this seemed to be neccesary today and electrical porsche parts are expensive)