Alan Dale for Gabriel Roman
Dale is a dead ringer for Roman, and has the awesome wily evil mastermind acting chops to back it up (e.g. Charles Widmore on "Lost"). Check out the comparison pics:
http://ps3media.ign.com/ps3/image/article/789/789108/uncharted-drakes-fortune-20070517035101829_640w.jpg
http://4.bp.blogspot.com/_cfPy3iBe3ag/SYHPpL9AjSI/AAAAAAAAAUI/J2mlQkmFDhA/s400/alan_dale_lost.jpg
For the hell of it, here's who I'd pick for the rest of the cast, also with pics:
Nathan Drake - Nathan Fillion
http://www.3dtotal.com/team/interviews/Richard_diamat/images/hero_render.jpg
http://www.sfuniverse.com/files/2009/03/krtphotoslive346449-enter-tv-castle.jpg
Elena Fisher - Anna Torv
http://www.shockya.com/news/wp-content/uploads/drakes_fortune_elena.jpg
http://resources3.news.com.au/images/2009/04/28/1225704/630823-anna-torv-in-the-fringe.jpg
Victor "Sully" Sullivan - William Hurt
http://i31.tinypic.com/vrq2xu.jpg
http://www.imdb.com/media/rm3494678016/nm0000458
Atoq Navarro - Benicio Del Toro
http://media.giantbomb.com/uploads/0/1041/245296-normal_navarro_copy_large.jpg
http://www.tracyjust.com/actors/images/index-benicio-del-toro.jpg
Eddy Raja - Kevin Alejandro
http://media.giantbomb.com/uploads/0/5365/255405-drakes_fortune_eddie_large.jpg
http://images.buddytv.com/articles/drive/images/kevin-alejandro.jpg