Is this a DD, or trial only rig? What shape is the motor in...by that I mean is it stock or does it have any mods? What is your major complaint now? Too sluggish off the line?
Personally the 20 rear should be good to go w/alloy 1 piece shafts. Yeah 44's would be nice, but under 250 hp, and not beating on it in a rock climb should be fine. My 304 lived through He!! when stock, and upgrades were considered exotic back in the '80s.
Truthfullness alert. When I needed an new frame I lucked out on an '86, that has a 44 rear. I put 4.10s in it to got w/a 400hp 360. It's not finished, so nothing to report.
The only "FINISHED CJ" is the stripped one in a junkyard w/a bent frame.