2. Go for an all DC system with a nice new Lucas RM21 or Sparx 005 single phase alternator and new regulator/rectifier. The wiring is simpler, it will have more power, you can wire in your Minda switch in the casquette, and fit a universal horn/dip/indicator switch on the left-hand handlebar. IF your existing alternator rotor still has plenty of magnetism you can probably save a few $$$ just by fitting the relevant stator, they are compatible.
Adrian, thanks alot, the above sounds like a plan, although due to the lockdown and it's consequences it will have to wait. I appreciate very much what you wrote ,if I was to stick to the 4wire, regarding help. I believe my reg/rectifier is a Swiss 790, does this function only with the present alternator or is this something that could be applied to the Lucas rm21, again, thanks alot