Clarendon, Fenice and some modified Times family from your computer library will be close.
Most of those things were lettered [or screened printed] long before computers were around... and were all done by hand. Most of the different railroads had their own painters and everyone just tried to get fancier than the next guy.... so the styles became more ornate with time. If you're trying to be authentic, you might have to combine some hand drawings or mutilate some fonts from your computer to capture the old look.
Try this site: http://www.haroldsfonts.com/frontpage.html
Particularly "Jim Dandy".
Lots of these are freeware or very inexpensive, and lots have that old-style feel.
I used some of them on the Dixie banner in the member galleries section.
The Fontry also sells Becker and Atkinson alphabets, not expensive, and some are very appropriate for that style.