Rims and tires

So you have 4 1/2 front space? Just making sure we haven't confused offset and back spacing. 14x7 is measured to the bead mount.

I would set the shock mounts on blocks to hold the car weight at ride height, install the rim and use a straight edge to find your distance from outer rim edge to fender lip. Then, allowing for tire bulge and safety, you can figure tire tread width and tire size.
Depending on your gearing you may want to adjust the tire aspect ratio.

With out knowing the actual width of your diff it is hard for anyone to give you a confident answer. We only assume its 57 inches.