I just wanted to drop in and say thanks for all the info in this thread! I picked up a '77 DT250 for cheap a few months ago, and have been working on getting it back on the road. I wanted to updated the lighting, and found this thread. I picked up the SH570-12 Reg/Rect and the Motobatt MB3U, as well as all LED signals, relay and head/taillight. Finally got it all wired up and it all works as it should! I even got the 30/45w LED headlight to work with no issues off the dc/battery circuit, and still have enough power to keep the battery charged with no issues! Have a Trail tech Vapor wired in as well with a working indicator dashboard!
Here is a short clip of it running! https://www.youtube.com/watch?v=cReT6Znp1g0