Well, glued it up and surprisingly it appears that it's gonna hold together. Working fine for the moment anyway so we'll see how it does over the long haul. After I put it back together I still couldn't get any continuity between the switch contacts at first. Thought maybe the copper parts were just worn down enough that they weren't making good contact with each other so I added a shim to push the two pieces closer together. Tried a fiber washer that I had on hand and it worked but made things a little snug so took it out and searched for something thinner. Ended up making one out of a plastic milk jug which turned out to be the perfect thickness. Key turns smoothly and stops and holds where it should, continuity everywhere it should be and nowhere it shouldn't. My horn now works but haven't looked into the rest of that circuit yet.

Couple pics of the switch, not a pretty fix with the glue but it works, it's OEM, and total cost was about 15 cents worth of glue.....

   

You have a lot more than 4 wires out of that switch. The one you posted wouldn't work too well 

Nice job on the repair!

Thanks Mark, Sure looks like there'd be more wires, looking at it from the back side don't it? There are certainly terminals for a lot more wires but most are empty. There's only four wires in there. Turning the key connects Red to Brown and Black to B/W, that's it.

Makes sense.  74 was the year they moved the lights on off to handle bar switch from key switch.
 

Great work (again!), Jack - a man after my own heart.

Photo of switch attached for reference.