I'm a little shorter than you(with the same inseam), very mannequin sized, and a 53 cm fits me very well. I would do the fit cycle thing(google it, I can't quite remember what it is called) with someone that is willing to measure you, and look at your possible fit styles(or if you know a good bike shop where people can decently eyeball your or cheaply evaluate you. My LBS has a guy that has 4 separate fit degrees that aren't bs, and it costs 250$ to have him do a fit session with you.). It really depends on your torso though. I ride a 55cm centurion road bike, and the TT is about the same which is why I chose the 53 cm.

You'll probably end up around a 53 or a 55, 50 would definitely be too small unless you have t-rex arms and can only reach into one pocket at a time. I do know a guy who is 6'6" who suffers from this, he is goofy looking as hell.

@adriano - your bike, is very sexy. I really like wheel lacing, and the use of moderate color. It also just looks very ride-able.