Repairing leaky drum brakes was the first thing I did when I got my 521. It was a great first experience of getting to know my car :) My reasoning is if your going to keep the drums, make sure they are in tip top shape. I had two leaky wheel cylinders so I went ahead and replaced all 4. While it was apart I got the drums resurfaced, replaced all rubber brake hose, and new shoes too. This is also a great time to repack your front wheel bearings if your up for it.
The whole process took way longer than expected but I am so glad I did it myself. I never knew how much satisfaction stepping on brakes could bring!
mmmm braakes