Plymouth duster rear suspension questions

Although the car is not in minitubbed. I would like to fit the widest tire possible that I can in the rear. I was under the assumption that relocating the springs inward would provide this clearance. So this is not correct?
Not unless you mini tub it. You cannot take advantage of the in frame leaf springs any more than the 1/2" relocation kit unless you cut the tubs in half and move the inner half against the frame rail. The inner half of the wheel tub is the limiting factor, since it's not up against the frame rail. So unless you plan on mini tubbing, the in frame leaf spring move is pointless.