let me suggest something in a slightly different direction. I chose to use an SPE 26cc in my Gp GeeBee which weighs only 2.5oz heavier than an OS Surpass 120 4 stroke glow. The less glow in my life the better. What I would do in your case is to install a dummy prop in the rear free spinning on a shaft on ball bearings. Stuff all the RX, pack, servos etc. as far to the rear as they will go and then run that SPE 26cc in the front. It puts out 12 lbs thrust. Two OS 70 surpass 4 strokes (within reccomended range) weight 44.1 Oz, with the one 26cc gasser it will weigh 6 oz LESS than with the two glows. It should fly nicely on that. As soon as that first engine fires the rear prop will be spinning. Other engines are available such as the 40cc version of the SPE26 which puts out 18Lbs thrust and weighs .8 lb heavier than the 26cc. No doubt that would be a FAST plane with all sorts of nice short field takeoffs like it did in Vietnam. You could go with flaps and slow the landing speed down too. Think about it this way, two OS 70 surpass engines that fit their reccomendation weigh in at 44.1 Oz, the 40cc SPE weighs in at 51oz. That gives you about 1/2 Lb more weight than the two glow engines and that would be easily dealt with. I think you can have your cake and eat it too. And let's face it, for less money and less hassle.