Reddit mentions of Singer's Musical Theatre Anthology - Volume 1: Baritone/Bass Book/Online Audio (Singer's Musical Theatre Anthology (Songbooks))

Depending on how much theatre you plan on doing, I would suggest picking up a compilation book and start working through some pieces that catch you eye. The Musical Theatre Anthology, v.1 is my personal favorite. For a guy your range, all the suggestions are good, I'd also throw in "Some Enchanted Evening" from South Pacific, maybe "Marian the Librarian" from Music Man, or "Reviewing the Situation" if you want to show off your patter.

I like to listen to a song, see if I like it, then start working on it. Some people will have a problem with that, and raise valid concerns, but I think that there's such a wealth of knowledge and experience to tap into, that it would be a waste not to use it. All the suggestions here are great, the key is to pick something you feel like you can have fun performing. Break a leg!