I think I'd want 4.10s with what you have. It's pretty economical, pulls well, but won't go to 7Krpm. I think a set of 4.10s would be fine and allow it to get up some speed with that 375hp.
I installed 4.56 gears in my Dodge Ram with stock wheels. I like it and my fuel economy got better. Of course the truck has overdrive is why I can get away with such a steep gear.
