I'm pretty sure you won't be using a straight drive shaft.
As you know the output shaft on the Busa sits on the starboard side of the engine and a straight drive shaft just won't fit.
Based on my dilemma (see the thread you are reading) the options were to do the electric starter and ring gear option, the electric winch (gear) and chain, or as just pay the money and buy a Quaife box.
I bought the Quaife.
If you are interested in exploring the starter and ring gear option there is a very nice fellow at Fisher Fury USA ( http://www.furyusa.com/ ) that told me that he can adapt a (Fury) electric starter reverse for a se7en.
By the way, I managed to incorporate most of the original "bike" drive shaft in the Quaife mod. I managed to save the front portion (the long telecoping bit) and install the Quaife box in the tunnel. I had to a couple of very short drive shafts made to mate to the Quaife Box.