Thanks for the information.
I ran a bunch of assumptions through my deep-dish spreadsheet and I estimate that for your 16" pie you will need about 2.6 times the amount of dough you used for the 9" pie. I can't give you an exact dough weight since that will depend on the final dough thickness which, in turn will depend on how you measure out the volumes of flour, water and oil, primarily. The rest of the ingredients will be small relative to the weights of the flour, water and oil. My best advice on measuring out the volumes is to try to be as consistent as possible, especially in measuring out the flour which is the most critical component from a weight standpoint. In other words, as much as possible each cup should be measured out just like the last one, not in a haphazard manner. In your case, you will be using over 5 cups.
Where the scale comes into the picture is to help you the next time you make the same pie. When you measure out the flour this time, I suggest that you weigh it (use the tare feature to zero out the container) and make a note of its weight. When you measure out the water, make sure that you view the liquid at eye level. The rest of the ingredients can be converted to weights by using standard conversion data, so I wouldn't worry about their weights at this point. Of course, to the extent you make changes as you prepare the dough you should note those changes so that they are available for use the next time you make the same size pie.
When you are ready to use the dough to make the pizza, I would weigh the empty 16" deep-dish pan and note its weight. If you plan to oil the pan before fitting the dough, I would weigh the pan with the oil in it. Hopefully the conversion factor I gave above (2.6) will allow you to use all of the dough in the pan without any left over. However, if you see that you have excess dough left over because of the particular thickness you settled on, set the excess aside and weight the pan with the fitted dough in it. With a simple math subtraction, we will be able to determine the actual weight of the dough fitted into the pan. I am guessing that the total dough weight will be around 36-39 ounces, so you might want to use that number as a rough cross check. If it turns out that you like the finished crust, and especially its thickness, then the next time you make the same pie (16"), you will have all the data you need to replicate the pie. Also, if you'd like, you will be able to create the corresponding baker's percents. With a little bit more work, it will also be possible to tweak the formulation to increase or decrease the thickness of the dough for use the next time. Quite frequently, it will take a few iterations to get the formulation where you want it.
Now that gottabedapan has spoken, I will add that I agree with everything he has said. One of the things you may want to keep in mind, however, is that if you load up your pie to the full 2" height of the pan you will have a monster pie that will affect the total bake time. I will defer to others who have made such a large pie, but you might consider using a slightly lower oven temperature (e.g., 425 degrees F) and a longer bake time to ensure that the center of the pie bakes before the crust overbakes. I think that will be the biggest challenge in making the pie. It is also one of the reasons why some professionals use heat sinks in their large deep-dish pies to achieve a uniform bake.
If you have any additional questions before you start your pizza, feel free to ask.