George,
I think there may be an easier and better way to proceed than starting with an amount of flour. Since we know the baker's percents and the thickness factor, all we need to know is how many pizzas and what size you want them to be. Then, we can use the expanded dough calculating tool at
http://www.pizzamaking.com/expanded_calculator.html to do all the number crunching for us. For example, if you want to make one 14" pizza, using the thickness factor 0.111 and the recited baker's percents in the tool yields the following:
Flour (100%): Water (42%): ADY (1.75%): Salt (1.75%): Corn Oil (24%): Total (169.5%):
 285.79 g  10.08 oz  0.63 lbs 120.03 g  4.23 oz  0.26 lbs 5 g  0.18 oz  0.01 lbs  1.32 tsp  0.44 tbsp 5 g  0.18 oz  0.01 lbs  0.9 tsp  0.3 tbsp 68.59 g  2.42 oz  0.15 lbs  5.08 tbsp  0.32 cups 484.42 g  17.09 oz  1.07 lbs  TF = 0.111

To convert the weights of flour and water to volumes measurements, you can use member November's MassVolume Conversion Calculator at
http://foodsim.toastguard.com/. If you use the pulldown menu to find the Gold Medal allpurpose flour, which we will use here as a proxy for whatever brand of allpurpose flour you will be using, and if you enter 10.08 oz. in the "Total" box and then click on the background, you will see that 10.08 oz. of flour converts to 2 cups + 1/4 c. + 1 T. + a bit less than 1/2 t. The flour has to be measured out in a specific way. Specifically, you should first stir the flour in the container to loosen it, and then lift the flour from the container using a tablespoon or scoop into the measuring cups just to the point of overflowing. You should then level off the tops of the measuring cups. You shouldn't shake or tamp the measuring cups on a surface.
To convert the water from weight to volume, you should use the pulldown menu to find the water (Fluid, Water) and enter 4.23 oz. in the Total box. You will see that the 4.23 oz. of water converts to 1/2 c. + 0.33 t. To measure out the 1/2cup amount, you should fill your measuring cup with water until the lower meniscus is at the 1/2c. marking. This should be done at eye level on a flat surface.
It is possible to start with 2 1/2 cups of flour as you requested, but you would have to first convert that amount of flour to a weight (November's tool can do this also), and then determine the weights of all of the other ingredients, and add them up. The total can then be used in the expanded dough calculating tool to determine the amounts, by volumes, of each of the ingredients other than water. You would have to use November's tool to convert the water to a volume measurement. I can walk you through the exercise in greater detail if you'd like, but I think the more accurate way to go is to use the method described above.
I think you can see from the above analysis why many of us prefer to work in weights rather than volumes.
Peter