Are you sure that wasn't 75 or earlier? I bought a brand new 76 KZ1000 off the showroom floor, which was the first year for that model. It replaced the KZ900. I also learned a few things about power when I twisted the grip on that beast.
Oh yea. Never forget your first.
"The original generation of Z bikes ended in 1975.
The next year, Kawasaki retagged the bike KZ900, and while it was much the same machine as its Z1 predacessors, the bicentennial edition featured some modest changes. Tuning alterations and smaller carbs shaved a few watts off the powerplant in an effort to refine the bike's raw grunt, but riding a KZ900 today precipitates a case of adult-onset deja vroom."
Here's the review in it's entirety:
http://www.motorcyclingmag.com/1976_kawasaki_kz900