Hey i own a Z1000J and i am thinking of mounting one my self. Did you succeed ? If not, look at this J from WrenchMonkees, i know it's a USD fork but i'm pretty sure the damper is mounted in one of the existing holes in the frame;
www.wrenchmonkees.com/motorcycles/monkee-8.html
The Moto Guzzi tank allows for the steep angle, but something like it should be possible..
Simon