I had one with an OS-50SX-H engine in it, which is a few ounces lighter than the Saito and still added weight to the tail. Have you flown it yet? Does it fly tail heavy or are you just worried about CoG before your first flight. If so just add some weight to the nose and graduallly remove it as you get comfortable with it. This plane is very gentle and predictable, it is a real floater.