I have used several engines in my 4 BalsaNovas. Webra 120, Saito 120, MVVS 144, Moki 1.8 and OS 1.6. I am currently flying the 1.6 and am completely happy with it. The Moki and the OS are very compareable in power, but the Moki is soooo sensitive to low speed mixture adjustments. I have been using J'Tec engine mounts.
I would suggest moving the elevator hinge line forward an inch and extending the rudder an inch and a half (rearward). On my next one, I will probably move the elevator an inch and a half and put aero balancers on the ends.
I am using 2 elevator servos, a digital on the rudder.
I also tried the FG cowl but liked the balsa more, even with the reduced space. I have not beefed up the fuse like in the above posts and have experienced no problems.
I agree with the idea of a 2 piece wing.
This is a thoroughly enjoyable plane. The only one any better (that I have had) is the Funtana.
Enjoy, Dale