[Arctic4lo]

The rims you need would be the "5-4.5 bolt pattern". What that means is:
5= number of lug nuts
4.5= 4 1/2" bolt circle. The bolt circle or lug pattern is the distance between two lugnuts, across the hub. Meaure the distance from head to head on any 2 lugnuts on the wheel that are the furthest away from each other (not right next to) and that is your lug pattern/bolt circle.
Early jeeps like CJs, and most dana 44 axles use the 5-5.5 pattern. The 6-6.5 is something you'd typically see on a half ton chevy truck, just as an example. And on most 1 ton trucks, you'd see an 8-6.5. That is "8 lugs" with 6.5" between the oppisite lug nuts.

Backspacing:
This is, in the simplest terms, the measurment defining how far towards the outer or inner lip of the rim the mounting surface is. With a higher numerical backspacing, the further towards the outer edge of the rim the mounting surface or "face" will be, causing the tire/rim to sit further back under the fender well. With a numerically lower measurment, the further towards the inside of the rim the mounting surface will be, thus pushing the whole tire/rim combo further OUT of the fender well.
With the options you listed, the 4 1/8" rim will cause your tires/rims to sit inside the fender a little more, and be mostly or completely covered by the flare, and the 3 5/8" rim will stick out just a little, and give a bit wider stance.