Mr Roseberry,
Without seeing the specific application I was simply giving an overview of the building process. I have a Lanier 35% giles with a zdz 80 installed, believe me when I tell you that the motor box had quite a bit of flex in it before it was reinforced. At minimum you need triangle stock around the motor box sides and bottom. Did you fuel proof your motor box and firewall? Lanier even recommends pinning the firewall to the box sides. I am confident that the engine box on my plane will not flex or break. I would rather add a few ounces of weight rather than have the motor box fail.