An evolution 15cc is the same size as a 60 glow motor. I have an early one on my flying king. the pumper carb should have fixed most of the issues... The early versions relied on muffler pressure and the muffler was a p.o.s. and would vibrate apart every 2-3 flights causing a deadstick. I ended up putting an os 91 muffler on it and no problems since. I would go with the dle20re and move the servos aft if it looked like it would be nose heavy. With the 78" wing it will carry the weight. And you can always run a three blade prop. The re motors are a very clean install and u would end up with the upper cowling unmolested and the exhaust dumping well below the fuse. I wouldnt go wild "beefing" it up. The sig airframe is plenty strong to begin with and you most likely would just be adding unnecessary weight. Good glue joints and a small bit of tri stock is enough