Some machining and everything can be made to fit. standard industrial parts can be bought and made to fit if you are industrious.
Don't they fly off more easily than v belts? I had a v belt fly off and the resulting overheating destroyed my motor. They'd not slip if that matters.

If you want somthing strange, you could try the v belts made up of a series of loops. They look quite odd "loopy" one might say. I've no idea of how good they are. Leavwe your fan blades on so there is something(wind)in reserve to turn the water pump if the belt fails.