I asked about this 6-8 months ago and found no joy. Basically, the custom rims will cost as much as true aftermarket cast rims. And you would have trouble with the front one mounting properly per it has a larger diameter than our stock rim & tire. You might could make it work if you swapped the fender also, but I would take good meaurements first. As for the rear wheel, I didn't get to deep into how well that would work after I realized the front one was going to be out of my price range and a pain to make fit. For what you are going to end up spending, you probably would be better off just getting aftermarket rims & tires that will fit without having to modify to much else on the bike. Good luck.
'07 VN900 Classic
Horsepower is an illusion.
Torque is the source of all good things.