12 volt conversion.
Hello, My outfit has a Chinamo, and Gardener 12v set up, it has work well for at least 10 years. This unit will not fit in the miller box, but is easy to hide under the battery platform. Low RPM output is not a problem, perhaps because being an outfit it is lower geared, so the motor is turning faster for a given road speed.
The solo has a miller dynamo with a 6V electronic regulator supplied by the late lamented Ken Bell. This unit fits in the miller box, and has given sterling service for around 20 years. Once again low RPM output is not a problem. He also did a 12v unit, I do not know if anyone still supplies these units, they are built to aircraft standards and work spot on.
My feeling is that unless you do a lot of night riding, or have coil ignition 6V is fine. Use a low wattage halogen head light bulb, and all will be well.
John.