Are you wanting to just concentrate on voice? If that's the case just go for voice.
There are schools such as DePaul, in Chicago, that have seperate programs for acting and musical theatre. MT programs are going to focus on dance and voice more most likely because as someone auditioning for a professional show you are more likely to get a chorus role than a lead. However, even in the chorus you need to know something about acting so you will still be required to have basic acting classes.
Currently~ Miss Myrna Thorn in Ruthless! the Musical
Recently~ Emma Carew (Jekyll & Hyde), Sister Mary Leo (Nunsense), Demeter (Cats), Tzeitel (Fiddler on the Roof)