Hi, guys,

I posted this on Photo.net, too. I apologize to those of you who might read it twice.

I recently took a picture of a church interior. The shadows (which I wanted to place in Zone III) and highlights were four stops apart. So far, so good. But in order to place the shadows in Zone III, I needed an exposure of 1 minute, which due to reciprocity correction became 12 minutes.
Lengthening the exposure to compensate for reciprocity failure also raises the contrast. I should probably pull the development, but by how much? Is there a formula? At least an approximate one? Should I try N-1? Or N-2?
Unfortunately, due to the long exposure time and the fact that I had already pushed my luck by mounting the tripod in a church, I couldn't take a backup exposure. I only have one sheet, so I only get one chance to develop it right.
Should I err on the side of underdeveloping, relying on the fact that adding contrast during printing will be easier than subtracting it? I'm aiming for wet darkroom printing.
The film in question is Fomapan 100.

Thank you.