Toby,
Thank you very much.
In order to see the total dough formula, I used your data in the preferment dough calculating tool at
http://www.pizzamaking.com/preferment_calculator.html. However, as I started to do that, I noted that your
levain weighs 350 grams, of which you apparently used 300 grams in the Final Dough. To use the preferment dough calculating tool, I first scaled your
levain down to 300 grams, as follows:
Levain00 Flour, 158.57 grams (100%)
Water, 115.71 grams (72.97%)
Storage starter, 25.71 grams (16.22%) (100% hydration)
Total: 300 grams
Note: Percents are with respect to the
levain flour
I then calculated the total formula flour and water based on the data you provided. For total formula flour, I got 941.43 grams, and for total formula water, I got 588.57 grams. Adding 23 grams of salt to these values yields a total dough weight of 1553 grams (of this, you apparently used 5 x 280 grams = 1400 grams).
The 300 grams of
levain represents (a) 31.87% of the total formula flour, (b) 50.97% of the total formula water, or (c) 19.32% of the total dough weight. For the preferment dough calculating tool, I used the 31.87% number but any of the other values will produce the identical result. The final number I needed for the preferment dough calculating tool was the percent of water in your
levain. I calculated a total water content of 128.57 grams and a total flour content of 171.43 grams (the combined total is 300 grams). Dividing 128.57 by 300 gave me 42.86% as the number to use in the tool.
After all was said and done, I ended up with the following:
Total Formula: 00 Flour (100%): Water (62.5190%): Salt (2.44309%): Total (164.96209%):
Preferment (Levain): 00 Flour: Water: Total:
Final Dough: 00 Flour: Water: Salt: Preferment (Levain): Total:
 941.43 g  33.21 oz  2.08 lbs 588.57 g  20.76 oz  1.3 lbs 23 g  0.81 oz  0.05 lbs  4.12 tsp  1.37 tbsp 1553 g  54.78 oz  3.42 lbs  TF = N/A 171.43 g  6.05 oz  0.38 lbs 128.57 g  4.54 oz  0.28 lbs 300 g  10.58 oz  0.66 lbs (Note: Preferment = 31.87% of the total formula flour weight; the preferment % of water = 42.86%
770 g  27.16 oz  1.7 lbs 460 g  16.23 oz  1.01 lbs 23 g  0.81 oz  0.05 lbs  4.12 tsp  1.37 tbsp 300 g  10.58 oz  0.66 lbs 1553 g  54.78 oz  3.42 lbs  TF = N/A

I realize that you have been using a somewhat different approach, but would you mind checking out my numbers and analysis? If everything is in order, one should be able to scale your dough formulation to a larger or smaller dough batch size using the preferment dough calculating tool. Of course, in making the
levain, users will have to apportion the
levain as you did between flour, water and the storage starter, using the percents specified above for the
levain, and using the prefermentation method you described. They would also use the method you described to make the Final Dough.
For 280 grams of dough for a roughly 11" pizza, that translates into a thickness factor of (280/28.35)/(3.14159 x 5.5 x 5.5) = 0.103927. That number should be usable in the preferment dough calculating tool but one might want to use a bowl residue compensation to compensate for dough losses during preparation. That value will vary depending on whether the dough is made by hand or using a machine. When I used the thickness factor option with the preferment dough calculating tool for 5 pizzas with dough ball weights of 270 grams, with no bowl residue compensation, I got the following:
Total Formula: 00 Flour (100%): Water (62.5190%): Salt (2.44309%): Total (164.96209%): Single Ball:
Preferment (Levain): Flour: Water: Total:
Final Dough: Flour: Water: Salt: Preferment (Levain): Total:
 848.68 g  29.94 oz  1.87 lbs 530.58 g  18.72 oz  1.17 lbs 20.73 g  0.73 oz  0.05 lbs  3.71 tsp  1.24 tbsp 1400 g  49.38 oz  3.09 lbs  TF = 0.103927 280 g  9.88 oz  0.62 lbs 154.54 g  5.45 oz  0.34 lbs 115.9 g  4.09 oz  0.26 lbs 270.44 g  9.54 oz  0.6 lbs
694.14 g  24.48 oz  1.53 lbs 414.68 g  14.63 oz  0.91 lbs 20.73 g  0.73 oz  0.05 lbs  3.71 tsp  1.24 tbsp 270.44 g  9.54 oz  0.6 lbs 1400 g  49.38 oz  3.09 lbs  TF = 0.103927

Note: Dough for five 11" pizzas; no bowl residue compensation
Peter