RE: Grumman Widgeon
You asked for input, and the input from Peter is that Brison 2.4's would be overkill. I agree with Peter. I fly my 51 lb. quarter scale with two Ryobi 31 cc engines.(And they are not very "hot" engines.) That is about 1.8 cubic inch. Keep the weight down, and don't load the 1/5 scale down with these two heavy engines. They would be more appropriate for the quarter scale, but severe overkill on a 1/5 scale, and way too heavy.