Hi, Gary,
Yes, your memory is still working OK. The headlight earth does go to the horn mounting. If you're using the old wire, checvk it's still OK, as they can break with continual flexing around the steering head.
The bike looks good, by the way. Never mind that i's not factory original colours, it's what looks good to you that matters. Don't forget to ride it when it's finished, though!
Graham
