Well then... That's easier then you think.
Check the DLS for Ben Dorsey's TOTC series passenger cars. You might have to fix the thumbnail thing if there is an issue with them, but other than that they should suit your needs. These are created with the capability of you 'customizing' the coach name, railroad name, and coach number by editing the config.txt files for the coaches in the series. There are older-style heavyweights and Harriman style cars in his available selection.
As I said before too that McGuirel updated and created some very nice Pullman cars which I think are suitable as well.
John