Depending on the style of pizza you decide to cook, 450 might be right, while 850 would be perfect for others. I personally have been preferring a very quick bake of one minute combined with a 800 degree oven, lower protein flour (harder to brown than high gluten) a really wet dough, and fresh or buffalo mozzarella. Last week I made an American style Sicilian pizza. For this recipe the dough had a lower hydration, the cheese was processed (not fresh), and the bake lasted 15 minutes at 500. Your recipe and style will determine your ideal temp and time.
Just because you have a brick oven does not mean that you have to fire it at 900 degrees. Bertucci's is an example of a pizzeria chain that has woodfired ovens that are fired at about the same temps as a cranked home oven. If you want to make a thicker pie, just don't get the fire raging, and leave the pie in longer. If you are having a hard time getting thicker pies cooked enough before the bottom burns try using a flour with less protein. This will allow you to bake the pie a little longer before browning sets in.