If you use billet wheels, the front wheel has hubs that bolt to the wheel. The rotors attach to those hubs. I was lucky enough to find these brand new at the time off a Ness KP. Also found the hubs and a rear pulley to match. Got a pretty good deal. The new wheels have a 6 bolt rotor pattern, so you have to find new rotors. Rylan has a kit you use that spaces the calipers to the rotors. Just have to run the front rotors backwards. Or, you can the hubs machined down a little to match the caliper spacing. You can use either a 16" or 18" rear wheel. The tire sizes come out to be the same diameter. I think it's a 180/55/R18 for the rear. I was just patient and checked eBay quite a bit.
victory wheel | eBay
I just checked the salvage place I got a motor from. Here is what you want for front hubs.
05 Victory Vegas Hammer Front Wheel Hubs
If you like the look, pretty darn sure cross bike or vision wheels would work with rylan's kit too. Still would have to come up with rotors. They have a 16" rear wheel and it takes a GL1800 rear tire. I use an Avon 180/60/R16 on the xct.