3:31 here, but you also have to calculate the transmission gears to get it "right".
I have a close ratio top loader, not the wide ratio. There is a BIG difference between the two in 1st gear ratio.
I shift into second at about 65 mph, thats not so much the rear gear as it is the combination of rear/trans gear.
Cruising rpm for me was about 2800 (4th. 1 to 1) but the motor like 3200 or higher better. SO, I'm changing cam profile to match my expected cruise rpm.
...I guess it's not a simple question.
If I had my choice I'd go with 3.31 and a wide ratio trans. If a 5 speed I'd go 3.5 or lower and PAY ATTENTION to what Ron said. The RIGHT 5th gear ratio is a MUST have!