I have solved this problem by using a later MB release bearing and modifying the housing, using a special seal and some machining of the carrier. The set up gives you a sealed bearing which eliminates central lube oil from the clutch area. Contact me if you are interested in having this done.
I should say, however, that I worked this out because there was no bearing available at the time. I don't know what Niemoeller is currently offering, if anything. They may now have something that works well and is a direct install.