Iron Clad, I'm suprised yours keeps up on the highway just fine...does it have stock rear end gearing too? Mine has the stock 4 speed and the 3:90 gears, it'll do 60-65 miles an hour...if there's no wind, and it's flat ground. If there's wind, a hill, or both, I have to floor it and it wont go over 55-60. Everyone does drive really fast here in Alberta though.
My truck has the 3 speed tranny. To be honest, I'm not sure what the rear differential gear ratio is. (You would think I should know by now!!!) Anyway, I routinely drive my truck 60 mph on the highway and the rpm's don't seem to be too high. My truck pulls the pass over Mt. Hood (6% grade) at 50+ in third gear, it could go faster but too many corners and you know how these trucks have body roll...... I will say that I prefer to drive the truck at 55 mph, for me there is no need for too much speed because I just enjoy driving it.
Back to your engine choice, I like the 6. I love to listen to the engine and tranny. as I'm going thru the gears, it's part of the experience. I believe swapping it for a V8 would take away from this experience. As said before, you could modify a 6 to fulfill your needs....
