Warning: This solution will require you to start the game over if you have already started playing.
If you haven't created a profile yet, you can skip all the steps that involve deleting files.
Go to gameDir\saves, and delete everything. Go to gameDir\system. Delete User.ini if it's there. Also, look for any .ini files with the same name as your profile (for example, the default profile name, Mason, has a file called Mason.ini), and delete them (editting them for FOV won't work).
Now edit the file DefUser.ini, and look for this part:
[Engine.PlayerController]
...
DefaultFOV=70.000000
Edit the DefaultFOV line to set your FOV. According to the FOV Calc, it should be 80.080645 for 16:10, and 86.073033 for 16:9.
Now launch the game and create a profile. The FOV will be correct (you can view User.ini and <profileName>.ini to confirm this). But, there is one major problem: The weapon selection interface is not only stretched, but the weapon icons themselves actually "jump" off of the interface. They jump so far that the description box for the Bulldog is no longer visible, and in the case of the grenade launcher, you actually have to move the mouse cursor off screen to the left in order to select it.
You can use Delphium's Field of View & Aspect Ratio Calculator .
You can adjust the size of the HUD via the following lines in Pariah.ini:
HudScale=
HudCanvasScale=
Weapon Upgrades: Upgrading weapons while in a wide screen resolution is difficult due to the HUD.
Keep your windowed viewport a 4:3 resolution and that way you can alt+enter to perform weapon upgrades.
