Rear wheel/tire size on 65 Barracuda

Does anyone out there happen to know the largest wheel/tire combo I can run on the rear of my 65 cuda? I would like to run 235/60R15 bfg's on 15x8 rallies. Although I will run even bigger if I can. I will be installing super stock leaf springs to bring the rear end up. I just can't stand the dragging tail look the car has had my whole life.

Any insight will be greatly appreciated.