'79 Wr390 Make Roadworthy

Hi all, I have what I believe is a WR390 Huskvarna that I want to convert from just bike to registerable (blinkers, lights etc).
Im happy to rewire but there appears to be little provision for battery and other bits. Closest Ive found wiring wise is a 360RT cicuit diagram with a single diode charge system.

Looking for advice from guy experienced in these bikes to point me to successful systems used. Should a go new with regulator etc or is there a system that works well on these bikes. Dont know output voltages of alternator yet of is you can load them down to good voltage?

Side pic