M_W,
Perhaps I missed it but you didn't say what license you hold and with which you'd be doing your DC3 flying. Wouldn't that affect where you could seek training ?
There are a few organizations in the USA doing DC3 training. I'd be surprised if any company using the airplane for commercial purposes other than training would be offering seat time or type rating to the general flying public.
Good luck with your project. You'll enjoy the airplane.
https://www.flyingmag.com/learn-to-fly-dc-3