I’m not aware of any railroad using Cooper Black Italicized.
But as Cooper Black is a standard font in Word, and like all the Word fonts can be italicized, why not make your own, or have someone do some decals for you (depending on colour)?
If you want black, Micro mark sell paper that will allow you to print from your inkjet printer.
If you want white or other colours, join the Yahoo Alpsdecal Group and ask if anyone will make the decals for you.
Alternatively, I have a mate with a Roland printer who will do the same job.
If you email my off group, I’ll give you his email address.