Hi Lonesome,
a drum brake in the rear of a B-model can be achieved by using the rear wheel and parts of (early) Z650s.
Gunnar has done it before and here are the pics of his bike:
http://www.z750twin.de/gunnar’s_b.htm
I will meet him at this years Z750Twin meeting in 3 and a half weeks. May ask him for details of what he has done.
Cheers, Michael
