You are going to HATE me! I am an ardent advocate for railway electrification! If I had these (though I must admit beautifully restored) I would remove (carefully) the actual diesel engines and set them aside. I would convert all these locos to pure (direct via pantograph) ELECTRIC! A large step-down transformer taking in 25 kV at single phase 50 Hz to 480 V, along with the rectifiers and other electronics in the hold where the diesel used to be. The fuel tank space would be used for back up batteries (for accessories). The rectify to 600 VDC for the traction motors via controller.The diesels I would use for MARITIME application either as generator sets (with AC generators at 50 Hz) or for propulsion engines (thus x 2).
It's a interesting idea, but where would they run? No preservation group could afford to electrify the tracks that they own and most of these locomotives aren't certified for mainline use.
I think you need to get a job as father Christmas then complain you have to work the 24th and 25th of December. Your idea is one of the most stupid things I have ever heard.
