Best rear end for my 62 235 I6 3 speed for highway use

[Dano0579]

What would be the best rear end to put in my 62 235 I6 3 on the tree truck to run on the interstate but still can pull a trailer if needed? I what to keep my 3 speed but I don't what it to run high RPM @ 70mph. I don't know if that's possible without changing my tranny but I have a brand new 3 speed floor shifter I want to use and just thought I would ask. Someone told me I would need a 4.11 rear end to accomplish that. Thanks for any help.