I don't know about any planes from the 1950s, but that would make a good addition for a Trainz route such as the PRR main line from Enola Yard to Pittsburgh.
I know that there is a DC3 somewhere, mainly because it was in 04, but I cannot find it. Good luck on the Enola Yard to the Pitt by the way. That is alot of mileage, and alot of mountainous region to cut through.