I'm a big guy, too. I'm not sure if you are in it for the cool project or you just need a good bike for the job.
If you are in it for a good bike for the job, have you considered an off-the-shelf road bike? They will hold your weight just fine. This way you can try before you buy. With custom builds from the ground up, you never get to ride it till you've bought and built it. Then you are committed. My last road bike was a Teshner built from the frame up. It was OK...then I rode a Specialized Tarmac and was like, "Holy sh*t this is nice..."
If you buy off the shelf, just avoid the ultra-light wheels. But, if you got a bike with such wheels, you can easily find someone to trade a beefier set for them. A road bike will definitely be easier to ride longer miles on than some other types of bikes.
Last edited by carleton; 12-27-10 at 02:54 AM.