I had a Fuji 50 in a Pitts and did use the short hub extender that comes with the 64. Fit perfectly so I had about 1/8 " clearance between the cowling and the spinner. The CE measurements are most likely a bit different that the Pitts, but the short shaft is an option. If you use the 64 hub extender make sure you also get the prop bolt. The threads are different between the 50 and the 64 hub extenders. Fuji may have resolved this by now, but this is what I had to do to get mine to work. Pictures are of Pitts-1 with the Fuji engine. Like NavyE6FE said, this engine flew the plane just fine. I lost it in a bad crash and putt a DA 50 in Pitts-II. The DA vibrates a bit more than the Fuji. Guess the big flywheel on the nose of the Fuji helps with this.