Adjusting priorities

I like your scenario, but would adjust some priorities. Saving the branch line you describe is probably more important that worrying about locomotive replicas right now. The most challenging and perishable part of railroad preservation right now is finding a place where a steam engine can run in a historically accurate environment, where the locomotive can be connected with the people it (or a similar one) served and the people who worked on and around it. Probably a similar higher priority is preserving appropriate rolling stock, both freight and passenger. This is why I think railroads like the EBT, the NN, and the C&TS are so important to railroad preservation. They can really tell a story.