So almost 2 years later I have found a Z1300 complete front end and thought I would share the outcome of this front end swap for others that is trying to get 18" in the front of a KZ650.
The KZ1000 police wheel that I got in the first place was never going to fit between the fork legs of the original fork. I could have opted for a never fork but I wanted the older style forks.
First I milled off the welds on both steering stems.
The 650 stem was smaller then the KZ1300 so I made a bushing to get a snug fit and then welded in the stem.
I then put new KZ650 bearings on and mounted everything.
The front forks will get spacers inside and maybe cut springs to lower the bike to the right ride hight!
Hope this thread helps someone in the future as so many threads have helped me!
/Marcus