You're killin' me!
On the KZ parts, a large caution based on a long legacy of making bad judgements and doing the wrong thing many times.
Free parts can be a curse sometimes. "Wow, look at these free....(insert part description here)! They didn't cost me anything!" Problem now is redesigning half your bike to make them fit. I learned a while ago that ANY part can be made to fit ANY bike, ANYwhere you want to put it. However, all it takes is every cent you have to machine up or have machined up all the interface or junction parts to make it happen. ANYTHING can be built! ANYTHING can be designed and fabricated, but at what cost in either time, effort or dollars?
So, that said, it's much easier to start with, using the Omar's wheel kit as an example, something that may cost you some investment, but you know (hope), it'll fit without any fuss and a minimum of frustration.
Having built a streetracker or two, I've had a bit of experience with things that work out bitchin' and some stuff that ends up really being a pain in the butt. That's why I suggest the Sportster rear hub. Maybe a KZ hub will work, but that's one I've never tried. Like to see a picture of it.
Here's some wisdom: figuring out wheel spacing and wheel centering is the hardest thing on earth to do. I've tried 118 different ways and it always requires remaking the spacers at least once!! Every time. I'll get it eventually. In concert with this is caliper hanger fabrication, disc and sprocket spacing, chain to tire/chain to inside of shocks, inside of frame rails in the swingarm pivot area, etc. Going to Super-Moto wheels could create wheel width, tire width or chain interference issues as well as the chain dragging on the swingarm issue. And you can't just run a teflon pad on the top of the swingarm and have the pad heavily loaded by the chain under power or the pad witll literally evaporate!
