I have a Tower .75 mounted on my UCD60, but I haven't gotten around to finish it yet. The Tower muffler acts almost like a mini tuned pipe and allows the .75 to breath well and make power. I don't doubt that it will hover it fine - just not at 1/3 throttle like folks who put other monster power plants on their UCD60.

I went with the Tower 75 because I have a whole lot of .75 2strokes lying around, so I picked the strongest one. This plane is built light and so I want to keep it flying light. I'm usually all for overpowering, but I read several folks having airframe structural problems with overpowering their UCD60. If you haven't bought the engine yet, he Magnum XLS .91 stroke is also a good choice, especially if you catch it on sale. I would NOT go any larger than .91 2 or 4 stroke.