I had to stay within a budget and it's the only thing I could find cheap enough. (and I knew nothing 'bout Harleys and know probably less now-- that thing rattled a few brain cells loose- er, I mean looser)
Interesting swap. If not for the cost issue, I'd say that if you really wanted to put a motorcycle engine in a Prius, why not a turboed Hayabusa engine. 11,000rpm Prius? Yes, please.
Keep in mind the magnetic motors in the front were stripped out as well. So he took weight off both ends. Weight distribution is for weenies. If the drive wheels are in the front, who needs weight in the rear?