I sold the Moto-Ski a few years back, it went to a good home (local moto-ski collector). When it left, it had a 440 Yamaha F/C bolted in. The motor worked great, even better than the 640 rotax I had in it previously.
The Moto-Ski is together and running. Boy is it ever fun. I have a 640 Rotax in it, and it will do donuts no problem! It's a pretty incredibly ride.
This is what the Moto-Ski would have looked like originally
I found a new seat for it.