I think the car was not driven much with overfilled oil. The owner said it was smoking heavily from the exhaust. He didn't dare to drive it. I took it on a trailer home. I haven't done much with the engine. It runs fine and does not smoke or consume oil. The clutch was a bit shaky first. Probably some motor oil on the clutch. It has become better after a while. Maybe I should check the breather as you say.
I am just mensioning this as a reminder of what can happen because of a broken dipstick. I know there are a lot of A2s with broken dipsticks out there. If your car consumes a lot of oil, check that you have the right amount of oil an a good dipstick.