I believe the correct thickness factor is 0.1266. I ran your numbers (baker's percents, pan size, total dough weight, dough depth, and 1/4-inch dough thickness) through my spreadsheet and got the above thickness factor number, which seems more in line with the thickness factors I have seen and used for deep-dish. Since I am still testing my spreadsheet for errors, I decided to do the calculations the old-fashioned way to see if the numbers match.
The total surface area of a deep-dish pan is equal the the sum of the surface area of the bottom of the pan plus the surface area of the side of the pan (I am assuming a straight side). Since the dough on the bottom of the pan uses up part of the depth of the side of the pan, by about 1/4-inch, that 1/4-inch should be subtracted from the depth of the pan or, in your case, from the depth of the dough in your pan (1.5 in.). So, if my premises and math are correct, this is what we get:
Surface area of the bottom of the pan = 3.14159 x 6 x 6 = 113.09616 sq. in. [This is pi times radius squared]
Surface area of the side of the pan = (3.14159 x 12) x (1.5 - 1/4) = 47.1234 sq. in. [This is pi times diameter--i.e., circumference--times adjusted depth of pan or, in your case, the dough]
Total surface area = 113.09616 + 47.1234 = 160.21956
Total dough weight = 575 g. = 20.282186 oz. [This is weight in grams divided by 28.35]
Thickness factor = 20.282186/160.21956 = 0.1265899
I left all the decimal places in so that your calculator will produce the same numbers. Of course, if the side of a pan is sloped, or if the pan depth (or dough depth) is different, the numbers will change. For example, if the side of the pan is sloped, then you have to calculate the surface area of a trapezoid--which is the shape of the side if it is laid out flat--plus tweak the answer to compensate for the 1/4-inch factor. Since my spreadsheet doesn't deal with sloping sides, I would have to use the old-fashioned brute force approach.