Without mini- tubbing the car it will be tight. You will need to roll the outer fender lips . Also get yourself a 3 lb and 4 lb hammers and go to work on the lower half of the inner fender wells. 5.0 magazine did a article on fitting 315's on a fox body. 10.5 or 11 inch rims will need a 6.5 bs at minimum .
Link to 5.0 article
http://www.mustang50magazine.com/tec...s/viewall.html