You'll be fine. I have an auto and can cruise on the highway at 70 with my 4.88's. I am looking to go lower because in mud (especially on a hill) in 4-high I don't have enough torque and 4 low (even prior to 4:1) was to slow (at least for my liking) and my plan is to go 5.36 and use 4-H for mud and hills I need speed on and 4-L (Tera 4:1) for the rocks.
What tire size do you run?