There are lots of examples of this mod if you look at the Pics section and look for Doornenburg 2006 you'll see 'Pascals' bike from Belgium, it will probably be at the Annual rally later this year.
Yes the engine does fit but you have problems with the oil tank in the way of the starter motor, you need a bigger battery and the radiator needs quite a bit of imagination.
Pascal cut out a portion of the oil tank and extended it backwards, then used K&N's which left enough space for the battery.
His work is in a Citroen garage so the 'plumbing' up front is a bit more industrial. But it works and gets him all over the place, like our Annual rally.
SteveD