Headlight switch ground?

[DJM]

300 miles in one weekend on your 50 year old bike, that's good going by any standards and great news.
Glad to have helped? solve your problem; wiring faults aren't usually difficult to sort out if you dopt a logical approach and, even after fifty years most of the Honda stuff is usually good, the faults mostly being in the wiring itself or the connections.
Hope ypu enjoy many more miles on your bike.