I've got two TF P-40's. One is still on the building board where it has been for about 2 years! I have a ST .75 in the other one with the in cowl muffler. Stay away from this combo. Mine is ten pounds and is tail heavy with not enough power with this combo. I'm putting a Saito 1.20 in it and from others I've talked to, this is the way to go. I'd say forget the gas engine unless you can find a very light model with a rear carb and exhaust. The corsair or P-47 would be better candidates for the G20ei. What stage of construction are you in? I've not done much to mine lately because joining the wings is so critical and I don't want to mess it up.