The OS engine in the right photo is an LA 40S and of course intended for controlline airplanes and the other is the throttled version.
Reinoks I beleve you are confusing Cubic Centimeters with Cubic Inchs. The LA 40 is .40 cubic inches about 6.5 cubic centimeters. These engines are totally unsuited to your airplane.
I would use no larger than an LA 10 (.10 cubic inchs) and as the guys already pointed out without three channels minimum you will have no throttle.
http://www2.towerhobbies.com/cgi-bin...&I=LXUJ71&P=RF
John