[crashz]

I concur with the advise above. I had 35" tires on my 83 with 4.10 gears and found that to be a good set up for towing and mild off-roading. I wouldn't go higher. 4.56 would be good too, but depends on availability.

It sounds like you are going to swap 3/4 ton axles in to simplify the gear swap, which is probably a good idea. The 10 bolt rear can get a little stretched with big tires and deep gears.