Updating... I looked all around for that piece of ring. I fished a magnet down in there and blew around with my air nozzle. Took oil pan back off too. Nothing... It didn't help that my wife swept the garage that day before I realized I was missing a piece. If it was on the floow I would never know now. I'm pretty confident it isn't down in my case.
Anyway, today I worked the electrics and brake caliper pad. The pad I bought off ebay was slightly too large and was hanging up in the backing plate. I grinded it down with a dremel tool. All good now.
Wired up a battery and figured out the neutral, oil, and turn signals lights for the instrument cluster. I found out my low beam doesn't work
Once I realized I had to ground that green lead near the coils (the coils aren't on it yet), I had my taillight and rear turn signals. So, high beam, all turn signals, horn, and turn signal buzzer all checked out.
Now waiting for my new ring set since I broke one installing it...