Mr. Bracket does indeed have some mad fabrication skills. I think I have watched his video dozens of times. That Honda is very nicely done.
Another Fat-Tire contemporary of his is located in Phoenix and is just starting to market a kit for the Yamahas. I think that it should have a very broad appeal since it should be able to cover 1999 to 2009 models of the 250s (both two and four stroke) 426s and 450s.
This is the website:
They are just getting their feet on the ground so things are still being ramped up. I'll try to keep the updates going here.