Ok, Finished my extra tonight also. Maiden tomorrow if weather permits. AUW is 6lb 14oz. wish it was a bit lighter, but we'll see how it flies. The gms .76 is also about 24 oz with muffler. She balanced a bit tail heavy. I put the rx batt right next to the engine and tank is directly behind engine in motor box. It balanced about 1/4" behind rec. cg. I think it will be fine as most of my 3d planes are tail heavy.
My biggest concern is how well this engine will run inverted.