I have the 4.0 OHV/manual tranny and 4.56/35s. At 55/60 it runs approximately 2k RPM or a hair over. If you currently have 4.10s try them, if you have 3.73 I would go ahead and get some 4.56s. I am pretty happy with this setup, but I don't drive over this speed very often.
Only reason I would get 4.88s is if its a trail truck or you see bigger tires in the near future. Oh, and I believe there is quite a difference between the 3.0/4.0 comparison.