Chris--My CG Sukhoi has been through 3 different engines. The most recent is a Bennett Built G26. I had a similar issue with this enging as one side extended out past the edge of the box. I used hardwood blocks epoxied to the side of the engine box, flush with the front. On the backside of the blocks, I use triangle stock in places where there is not mounting bolt. You can also pin the block to the engine box, but at least on mine, this has not been necessary. This only took a little bit of time and has proved to be very strong and reliable. The plane flies great with the engine and an APC 18x6W prop. A little higer wing loading than my old YS140L had, but the plane still flies great. You'll love the plane and it should be a good combo with the engine you have. Good luck.

Ron