Hullo Hencam,a rod brake is the best for feel & is nice & positive when correctly set up. If not being totally original is no objection,a Pursang hub would give you a sprocket on the left with brake drum on the right,job done! Er,not quite. Most of these had a chrome surface direct onto the alloy & over the years most of them had peeling off troubles. The answer is a steel insert. You could use a Metralla hub,but these are rather big & quite heavy,also a road M.Z. Hub would do,but it uses a cable although that would be short & on the same side. I think the very early Lobito had sprocket & drum is on opposite sides,this could be the answer if you can find one. For me,I much prefer left brake. Most people these days have a car that is with an auto box & use left foot braking,I do so to be on 2 wheels is a follow on from this. Hope this helps a bit,keep us posted on any developments,John.

How about a hub from a later model alpina. ? That'd work perfect

Steve