You cannot put a 12" Z on without changing cables. !0" yes, 12" no. I was thinking something along these lines. //http://www.grcustoms.com/shop/125-Z-Bars/

 

Had these on mine with stock cable I think I just bent the trottle cable to angle i down a bit thats all rode fine, (bent the metal bit by the throttle housing)

 

I have already installed 12 inch Z bars on my bike using stock brake cable. I'm not taking a educated guess I actually already did it.