Here is what I did on my Zero. I have used similar spinner to this ones

http://shop.lindinger.at/product_inf...ducts_id=48161

http://shop.lindinger.at/product_inf...ducts_id=44909

mine is even bigger 95mm diameter but for me it is not ugly because I do not have dummy engine so there is not big hole in front of engine.
Good think is that there is enough air flow or cooling engine and i did not have to cut lot of canopy for air to go out.
As you know, exit hole has to be at least 2,5 times bigger than intake. And of course, at that price you do not have to make it.