That is a nice R100. I'm rebuilding a '74 R90/6 and have a thread on this site, kinda. I work on the bike when I can, I'm kinda in a lull at the moment. The frame is off getting some work done. A buddy is doing his work for me at the right price, free. Been in a holding pattern for a while, Any way, do a web search- Classic Bavarian Bagger. It should come up. It will show you some of the things you run into a bike build. You learn important things like perserverance, patience, trial and error, sticktoativeism, all kind of neat stuff.