I've not tried it, so I can't comment from experience. I'm just thinking about making something similar if/when I decide on a 4* or Venture 60.

Bear in mind that the cowl slopes inward from the original fusalage so that on a side mounted engine there will be a fair amount of the cylinder still in the airflow. Probably more than with a fully enclosed fiberglass cowl... Also, the muffler is out in the open too...