I just got back from the hobby shop where I went to see if I could find a strong servo with a shorter case to fit in my wing. While there I met a guy who flies a Ziroli Crsair and a P-40. He says two servos on one aileron is overkill. Ask ten people a question and get ten different answers! Seems to me one servo is not spreading the load out enough for a long aileron (probably about 20"). Would two servos of about 70 0z. (I think that was the torque) work ok? This is a Ziroli DC-3 that obviously will not be aerobatic, just slow scale flight. Almost everything I read says use two servos but here's a man who is using just one.
Granted, the Corsair is not as big as the DC-3 but still a sizable plane.
Everyone in the shop at least agreed that pushrods and bellcranks from one servo is not the way to go, as Twinwar pointed out already. I agree with him and now have to figure out which way to go with servos....one or two.