Rear gear help

its a stroker, I would use 3.55 or even 3.23

4.30's would be great in a 340

but then you say you go 60 mph only on the freeway's, well then 3.91 would work well. I go 75 mph and its a steady 4,000 rpm's...little 340 seems very happy cruising at that speed or quicker but 3,000 rpm is more pleasant but I can't drive 55