I have a 70 model myself. I have late model switch clusters though and a late model complete front end. (disc brake, big headlight shell without the halo, etc) Somewhere in the late 80's I added the wiring to put directionals on rear of my bike. Later when I added the fairing, I added the front directionals on the fairing.
I created my own wiring mini harness in all dark green wire, so any green wires on my bike are for the directional system with the exception of the switch wiring which was already in that instrument cluster's wiring harness. The stock lucas flasher unit didn't work, so I used a 12volt flasher out of an old dodge pickup truck and that worked for 20 years, then I replaced it with a "mostop" unit, which is a flasher that can be set to be self canceling. It's works well, and it keeps me from riding around with my blinker on
I just added the wiring for my directionals and left my working harness for everything else alone. The stock directional fixtures are chromed plastic, so the grounding to them is not great. For every directional light, I added a ground wire to the grounding point on each fixture to bring that ground point back to a solid mounting point on the frame. Before I added that extra grounding, occasionally a light wouldn't blink and jiggling it would restore functionality. After I added the extra grounding, that never happened anymore.
Having directional lights is a good thing. Young people driving today never used hand signals or ever saw them regularly used in their lifetime, so you can never be sure they know you are signalling. It's worth adding them for a little added safety...