Here's the easiest test in the world: Drive your next highway run in SECOND gear at 70MPH for 90 miles. Do not shift into drive!
You can figure 355's or 391s will give you about the same highway run.
You will get a first gear lower than your current one for burnouts and acceleration, but your current second gear will become your drive gear.
Numbers on a page are all speculative. When you listen to that engine whine in second gear for 90 miles, I think you'll want to keep what you've got or go with an overdrive.
My 2006 Dodge truck with a 6 speed overdrive goes 1900 at 70. I can't imagine running 3000 rpms for 100 miles!
