Hi!
I don't want to upset you in any way but those .52 twostrokes will make your DC- 3 fly like a pattern plane.
20 years ago a friend of mine built the same DC-3 as you are building from M:A:N plans and he used OS .45 FSR:s and those where way too powerful.
I would recommend smaller and lighter engines like the OS 32 or OS .40 LA using 10x5-10x6 three blade props.