Bottom rack & 450 is plently, you don't any more heat than that to bake Sicilian.
Matt, while that is true, I personally prefer the faster cooking times of the 550°F setting, with finishing directly under the broiler. But then again, I am also using a much heavier amount of cheeses on my Square (which is not really Sicilian at all), so the hotter temp helps. But I also notice a more open and airy crumb at the hotter temperatures.....particularly when done at 750°F or so, but that's another story.
It varies depending on what each individual is looking for and no one way is "right". --K