I had a RVF400 front end on my mc21 until recently, its a very easy modification and seemed to work well. Updates the looks and looks like oem fitment plus you get the bigger discs and improved braking. You do loose a bit of steering lock though, the wider spaced USD forks hit the radiator unless you reduce the lock.
You need to remove the stem from your nsr yoke and fit it to the rvf yoke and use a Tyga steering lock reducer, although Tyga now make a rather nice set of billet yolks to suit this conversion if you want to push the boat out.
These are the RVF parts you need:
