A poet and R&B artist you might want to explore and include in your research is Saul Williams. He is actually known for his blend of poetry and hip hop. He has published books of poetry as well as musical albums, both of which could be used as material for your paper.
I think it depends largely on which specific lyrics you are wanting to use as evidence and which particular poets and/or poetic movements upon which you want to focus.
For example, a great deal has been written on the late English Romantic poets (Byron, Shelly, Keats) and their influence on Tupac and the similarities between some of the themes and devices used in their works. See the website below for more information.
You might benefit from trying to analyse the lyrics to a rap/hip hop song in much the same way as you would analyse a poem. I remember trying to teach metaphors to an Afro-Caribbean student and what clinched the lesson for him was identifying a metaphor in one of his favourite hip hop songs that described the singer to a rose growing up in a wilderness.
I think that much of this is going to be dependent on what rap you are going to be using and what particular artists you wish to link. Short answer is that you can probably find much in way of similarity between rap artists and certain poets. For example, I think that you might want to investigate the writings of Amiri Baraka. The level of anger, nationalistic identity, as well as the call for change is something that can be seen in the rap of artists/ groups like Public Enemy, KRS- One, or Tribe Called Qwest. I think that you can find much in way of the anger and resentment in many of Baraka's work as can be found in the lyrics of N.W.A. When he writes about how "walking the dog" can cause the "ground to envelop me," one can find some paralell to the lyrics of "Straight Outta Compton." It would be really interesting to paralell Baraka's Marxist beliefs with Eminem, specifically "The Eminem Show." In both of these artists, we see how class plays a defining role in one's existence. I think that these could be starting points on linking rap with poetry.