Hi Scott,
International Rescue here.! I've also got a DT 175 MX 1978 round tube swinging arm bike. I've got a photo of the loom under the tank if that helps, and I'm more than willing to take my tank off and photo around for you.
I'm familiar with the electrics of this bike, see one of my main popular posts on 12v conversion if you're interested.
I can send you the photos, if you PM me if thats any help. Plus if you happen to reside on the South Coast I could simply show you.