There is an alleged american source, I think I have seen that in http://www.ziggysmotorworks.com/inindex.htm
In Europe the source I would try is IPE first http://www.indianpartseurope.com/
then Jurgen Hecker http://hecker101.de/en/.
And RENO. http://reno.indianmoto.cz/index.php?id_category=24&controller=category&id_lang=1
If you have Facebook you can try contact Otto Knerr https://www.facebook.com/otto.knerr?fref=ts