:cheers:
Anything is possible, it wouldnt be a simple bolt in operation however.
Do you have the time and patience?
You would need to aquire a good running 787 engine, it would need to be a complete longblock assembly, as nothing from the 650 is interchangeable.
The front engine mounts will need to be removed from the hull liner as they would be useless, you would need to glass in a new tork box that the rubber engine mount bolts to. This is the front center mount specific to the 787.
It is important during this process that the new mount is fitted properly to ensure proper engine alignment. Other than that just run your fuel lines for the dual carbs, install your electronics.
But in all honesty you would probably be better off just trying to find a deal on an x4 with a 787 in it. Look around, the late nineties spx's are just and older xp with an spx badge. It will save you alot of aggravation, and the x4's are a better ride than that 93 xp hull.