Hey Tony,
I reckon with a bit of 'shed time' you could get an SP370 engine in there...
I know you have a few spares so it would only cost your time. 
VMX42
Wash your mouth out!

Why would you ruin a beautiful, rare, exotic bike by putting it in an Ossa chassis.......

And yeah, shortshifter, I'm surprised at how easy bit seem to be to come by.
There's a couple in front of it in the queue, but I am looking forward to owning my first ever plonker.

P.S. thanks for the heads up on this one, Paul.