Sourdough dough size and baking time

I am going to bake a dough that is about 3 lbs. According to the recipe that I follow, the dough is supposed to be divided into two and baked as two loaves, but I want to bake one big loaf. According to the recipe, each loaf should be baked in a covered Dutch Oven for 30 min at 500F first and then at 450F for 15-20 min uncovered. But since I want to bake one large dough, should the baking time be lengthened and how much longer do you think I should bake the bread? Thanks!