Rear tire width max for 67 Barracuda

I scored an almost brand new set of 15 x 8 inch Cragar SS with the 4 inch pattern and 295\50/15 BF Goodrich tires. Bolted right in but felt they were too close to the leaf spring so added a 5/16" spacer and man, do they look sweet under there now. Running 155/80/15 up front.
4 1/4 inch of backspacing by my measurements.