We can never say never. I understand the historical significance but 483 is bigger and 478 would have required a ton of work and might as well be close to the same as 483 in $$$ and man hours to get her running. If we're going to "play trains" we need to think about the current and future of the C&TSRR historically, yes, but mainly operationally. 478 is older and has ran continuously, it's boiler is probably in worse shape than 483. 478 would have never ran on the C&TSRR unless a railfan with lots of dough wanted to restore it. Like you said "other and better candidates." I'd rather see 497 or 492 which would make sense operational as it can handle another car up the hill.
Don't get me wrong, if we threw logistics out the window I'd love to see a K-28 on the C&TSRR, it would be beautiful but it doesn't make sense. I might even bite if 478 was actually in great condition and had just gotten a 1472.