Paint's a pretty technical subject.

Glasurit paint is pretty $$$$. Proud of it, they are. Maybe begin by looking over some color charts at your local auto body supply store. Unless you plan a full concours restoration, select a color that you like and will compliment the R65's design features.
I painted my '83 R65 in a metallic blue that was used on a BMW F800. I located a perfect match off a Honda automobile.
BTW, There's a BMW Airhead that turns up at most every major BMW rally. It's painted just like the machine behind your bike. Truth. Figure if you don't go beyond that Deere, you'll be fine.