So I haven't done it on a busa but did swap the front end on an old srad 600 with the front end off an 06 600 (think it was 06). The used the same bearings in the neck so it all fit just had to have the parts off the 06 like calipers, axle, clip ons, etc. Pretty sure I ran across a thread or twin in here where what your asking about has been dune and I think they said it was a direct swap.