Excelant find. It may start with a carb cleaning. Check the oil, trans, and rear end to make sure threr is no water in oils. Check that the tank is not rusted. You can hunt down most any part you need for it. Join the BMW Vintage club it will help you greatly also the Internet BMW riders and the BMWMOA. If I could still work on them I would be trying to get it away from you. They are simple to work on.
Oldyardog