Spring Relocation and tire size

I have 245/45/17 on the back of my 66 without relocating the springs. They rub a little on the inside of the wheel house. I have about 3/8-1/2 inch clearance between the spring and the tire.
Even with the spring kit you'll probably need to mini tub to get a larger tire in there. The wheel houses aren't very big on the early A-bodies.