My Goodness. A triple century every day. I think I would pursue pro-cycling rather than messengering if I were you. 300 a week is quite a bit too, considering that that would be around 15,000 miles a year. Most Semi-Serious roadies that I know put in about 2.5-4 thousand every year.
Crazy man. If thats legit then you have my respect.
Oh, and since no one mentioned it, use an ENO hub on a carbon road frame. More forgiving geometry of a road bike, brake holes, the whole shebang.