Clifford, I think two .61 four strokes would be plenty. The .70's I use give more than a scale power amount, to be sure, even though the rear engine is probably closer in power to one of your .61's.

On that note, I just got back from the field. There was about a 5-8 mph crosswind, but I took off without fear knowing that the Skymaster can handle it. Let me tell you, it was a fun time. The O.S. FL-70 actually started the day running pretty well. I can't seem to get it to lean out on the low end and still run even a little bit reliably. The tank is below the needle by about 1/2", so it really shouldn't be flooding. I'm pondering sending that engine back. I landed twice today with it having quit. The Magnum, on the other hand, is a freakin' powerhouse! That thing is just barely breaking in, and its power just keeps getting better. It is louder than the O.S. by quite a bit, but it's worth it considering how much better it runs. It idles very reliably, mid-range is smooth to run in and transition through, and the high end is significantly more powerful than the O.S. Now, it does consume quite a bit more fuel, but I'm okay trading that fuel for a decent run.

I had some excitement today when, on the first flight, both engines were running great and I was doing touch-and-go's, one after another, with flaps and without. I took off on the last one and the Magnum got some air bubbles due to the fuel level getting low and stopped when I was climbing out at a high attitude, about 30' in the air. I nosed forward to level flight and circled around, with the flaps down, still able to climb slightly! I landed without incident and fueled it up for the next flight =)

Seriously, this airplane is a heck of a lot of fun. Sure, it can't fly inverted for very long and it won't do any 3D maneuvers, but it is a fantastic sight to see in the air... and it has a VERY UNIQUE sound, (when both engines are running).

I really love this airplane!!