Congratulations on being in your final semester!
My school wouldn't allow us to precept in anything but med-surg, ER, IMC, or ICU. Their reasoning was that students that precepted in specialties were good students, but usually didn't pass NCLEX because they didn't have enough med-surg experience. I guess I can see where they were coming from, but NCLEX is all textbook nursing anyway, not the shortcuts you learn from other nurses.
If I had been given the chance, I definitely would have precepted in the specialty that I really wanted! So I would say go for it, work hard, be eager to learn, and make nice with the floor nurses and unit manager, and give her your resume at the end of your preceptorship!