It'll be frowned upon on the forum, but I might recommend looking into Suzuki TLS/R motors, as with a bit of work they'll slot into the 916's frame.
There's plenty of information out there as to how (with a few choice parts) you can slot it in (you'll need hangers from a Cagiva).
Cheap(er), reliable and well... provides motion.
Not a Duc' though.
G