I can't speak for the six, because I've never had one that was set up well. However, I'm sure you can make one pull.

On the other side, I'm running a 350, 4 speed Saginaw, and 3:38 rear gears. I've pulled quite a few trailers with the '58. Most of the time hauling a vehicle. The truck has good low end torque as well as being able to run 70 loaded. You'd be hard pressed to talk me into swapping for a 6.