Have you considered Lucy? She has an amazing orange gown/nightgown in the Coppola movie.

If you're interested in any of the Coppola version movie costumes, by the way, the Holy Grail of reference pics is here:

http://www.costumersguide.com/cr_dracula.shtml

If you're wanting to go an easier route for Mina Harker, there's the also recognizeable and less detailed version from League of Extraordinary Gentlemen. She has a couple of outfits:

http://www.alleycatscratch.com/exhibit/AMPD_FIDM/2004/LoEG/100_5050_SE_fi04.jpg
http://www.moviefans.de/a-z/l/league-of-extraordinary-gentlemen/mina-harker.jpg