Have a look in the owners Doc. The 01 and 07 frame are very different in angles and the like, but the engine is essentialy the same. The frame for 400 through 650 is the same, the difference is in the year models.
besides the head angle change in 2004 (or 5 - i've not looked) the only real difference is the coil mounting. and the early frame has an earth wire carousel. other than that there are no real problems to overcome.