Never mind, I figured it out. Last week I didn't even know how to read a wiring diagram, but this week I think I should have had most of these problems sorted...hopefully. The PO clearly ripped everything apart at one point and massacred a lot of connections; he rewired the front headlight to turn on high-beam and rewired the starter button to an ugly RadioShack toggle switch above the instrument light panel. The goal was to return everything to stock form.
Spliced in the wires from a new set of right-hand controls I got off eBay. It came with a box connector at first that I cut off.
Where does this green connector go, if anywhere? On the diagram there's one green wire that's marked as a ground for the frame, I suspect this must be it...all the other green wires are accounted for.
Tagged all the ends that connect at the front end, inside the headlight housing. (What a nightmare.)
Finished, tagged, retaped, and ready for installation!
Also, the PO removed both the turn signal buzzer and the clutch safety switch. He ended up connecting the brown/blue wire from the buzzer into the green/red wire of the clutch switch. I guess that should be the end of that, unless you guys have a better idea of what to do with those loose wires.