biggest tire for a 75 duster.......

ok guys i am a noob when it comes to the A body. I am getting ready to cut up the wheel well and minitub the rear end, but i want the biggest tire that will fit. i would like to go with a 31 in tire 12-14 in wide but if that is too large for a mini tub then so be it. I havent looked or measured anything yet. I would like to know what will fit then the problem i run into is finding a set of slicks and street tires the same size or close to the same size. keep in mind the car does not have a rear end or wheels yet so tire size will help determine the wheels and axle width. thanks in advance for the help.