don't really think it would be to bad.  you would have to use all the gears, but that's what they are there for.  i have a 13 in mine with 3.73's but never use L, 1, or 2.  also you probably wouldn't use overdrive on the top side running 2 lane roads.  i do have a chart that you can put in the rear end ratio and tire size and it will give you rpm's at any given speed in each gear.  i think i got it off eatons web site.