I have ridden a regular road bike successfully at up to 245 lbs.

You might want to consider a "custom" frame.

I think the ideal for you would be a touring bike - more relaxed geometry, built to withhold heavy loads, more comfortable, looks like a road bike. Also a cyclocross, built tough for tough competition.

Good luck and have fun.

By the way, I weighed 214.5 lbs this am, my lowest in a lloonngg time!