hello
as you hunt for parts for the rebuild keep this site in your links list
http://www.mz-b.de
they make replacement electrical parts for old german and many
european bikes and may have what you need to up grade
yours to a 12 volt system if it is a copy of a MZ model
or used a MZ built motor
if the bike is a copy or clone they may be able to help with parts
and they have an english section to the web site
they also do a nice one for bmw r50 /2and r60 /2 and r26 r27 r25/3 250cc models makes them run much better its one of the best thing that can happen to an old bmw or mz
ar dave