My previous project had mini tubs that had 1.250" additional depth added. It'll all depend on what you do with the lower control arm..the spring mount affects inner wheel tub possibilities. My red car had 11" wide wheels with a 7.2" back spacing. After mini tubbing I added coil overs, and did away with the factory upper spring mounts. ( if you're gonna do a mini tub, you may as well open the potential depth to as much as the frame rail will allow).
Properly done, you should be able to accomodate a 315/335 tire back their after a mini tub.