I'm looking into the same project for my 750K3, I want to keep the stock tire sizes if possible, as well as my drum rear brake. 1980 KZ650F had a 18" rear that fits the bill, now to find one... 7 spoke morris knockoffs were on tons of Kawi models, no problem finding a 19" dual disk front, maybe I'll even upgrade to a complete front end while I'm at it, I wonder if the speedo-drive cable will work with my stock clock? 16" rear wheels with the drum brake are plentiful, maybe I'll have to think about it... I understand that 17mm axles were the Kawi way, simple stepped spacers would adapt the axle to the swingarm, or go with different bearings to allow a stock honda axle. Here's a pic of a KZ650 with the 7 spoke wheels, I think I'd like to polish mine and powder coat clear.