Building a second oven

We are building a second oven for commercial use. We want to make it 1800 mm inside diameter. The oven plans only show dimensions for a 36" (914 mm) and 42" (1066 mm) ovens. We want to build the low vault version. These plans show the interior height, opening width and opening height increasing 1" for the 6" of increase in interior diameter.

Does anyone have experience with a larger version as far as these dimensions are concerned?

This oven will be built in a restaurant where we expect to sell between 250 to 400 pies a day with roughly 40% 11" pies and 60% 16" pies. We have access to fairly high grade had wood, a fruit wood of some sort. The restaurant is in a new mall and we will install a spark filter/arrestor on the oven so the hood fan only get smoke - fairly white.

Our calculations suggest an interior height of 21" (533 mm), an opening width of 23.5" (596 mm) and an opening height of 15.5" (393 mm). Will be very appreciative for information and corrections on these dimensions and any other comments on commercial use of this design for ovens.

If anyone has the engineering/math skills to deal with this issue, we are most interested in a contract with you to give us a safe design we can build (with blueprints).