Powerwise, anything in the 600 class is going to pull you along just fine. With rear wheel horsepower near the 100s, they won't even notice whether you weigh 180lbs. or 280 lbs.
For a commute such as yours, someone of your height would probably not want to be want to be in a sportbike crouch for 40 miles. There are bikes in the 600 class that are more ergonomically suited for the regular commuter (and less expensive!). The power is still there, but the cams and induction system are tuned for a more streetable power band. Check out some of these :
Honda 599
Yam FZ6
Kaw Z750s
Suz Katana 600
All of the above make nearly 100 hp, so they'll move you pretty easily. Just a little more comfortably than the full blown sportbikes.
