Here's a great article with plenty of pictures I dug up that details the installation of 315/35/17 tires on the back of a Fox Mustang. It's a good article. Since 87-88 Birds and Cats have a little more clearance than Fox Stangs in their rear fenderwells, we should have an even easier time getting meats like that to fit.
http://www.mustang50magazine.com/techarticles/m5lp_0806_fox_mustang_wheels/index.html