HI!
It should not be that much work getting this DC-3 fixed!
The problem with the wash-in in the wings are rather easy to fix.
As they are foam wings they have to be cut lenght wise so that it is possible to twist each wing so that you get wash-out instead of wash-in.
Take a sharp bread knife or Japanese fine toothed saw and start to cut / saw the wing from the inner part to the tip .
I would choose to remove the plastic covering before I do this.
When you have made 3-5 long cuts 3-5cm apart you will feel how flimsy the wing is..or should I say how easily it is to twist the wing.
Now you have to fill the cuts with white glue or Aliphatic resin...or epoxy covering resin.
Use tape to hold the wing in shape and see too that you get the wing twisted in the right direction (some wash-out).
Doing this right is going to make the Kyosho DC-3 fly OK...I hope.
Build it light and I'm certain that this airplane will fly just fine
Here is my scale 3-blade 10x5 carbon prop for my Marutaka DC-3 (span 211cm). Engine is OS FS .26. This engine turns this prop at 9200-9500rpm on 5% nitro and 15% Motul "Micro" all synthetic oil.
Regards!
Jan K
Sweden