I checked the dimentions, and think I understand your clearance issue with the engine. No matter what engine you install, the position of the williams bothers dummy engine crank case will have to be sacrificed a little in order to allow the engine drive hub to extend through so the cowel fits on. I would use a dremel or similar roto tool with a 1/2 inch sanding disc to gradually open up the center of the crank case until the prop drive hub clears through it to reach the front edge of the cowl. You will loose some crank case detail, but the rest of the dummy engine looks so much better than the one supplied with the ARF, I would stick with it for the cylinder head looks. Hope this helps, and provides a possible solution for you. I have not installed my wing fairings yet, but I have read some guys had to do a little trimming to get them to fit flush to the fuse, and wing. I am hoping to tape them to the fuse with blue painters tape along the seam, once aligned properly, then begin gluing them securely from the inside, to prevent messy glue from oozing onto the fuse. Pete