UCD and Tower .75?
Those Tower engines seem to pump out good power for their class. But it seems that people either swear by them or swear at them. To be honest I've never owned one. I have heard more good things about the tower mufflers than I have the engines. The number one complaint I've hard about tower engines concern the carb. Apparently they are notorious for having air leaks in the carb. They may have updated them in recent month's though. I'm not really sure.
My gut feeling is that the Tower 75 would fly the plane OK, but I don't believe it will be a great engine for hovering or other manuvers that require lots of torque.