After watching that clip of your turbine pulling the dump cars, I think part of why it looks good to me is because of consistency. I think mixing postwar and modern rolling stock can be tricky because the brain notices the difference. But when it's 90% of one and just 10% of the other, the brain doesn't seem to mind. I think you can get away with a lot of "unrealistic" stuff as long as you're consistent. It will look like it belongs and that's what works.
That's my two cents. Doesn't really matter though. You can run whatever you please because it's your railroad and that's one of my favorite parts of this hobby. A creative backstory satisfies any beef someone has with how I've done something haha
