They come from the factory with mismatched ratio's like that. It isn't an issue. And yes you can use it on icy roads along with snow covered roads.

Now cheapin out and going with the minimum install kits isn't a smart move. Save your money and buy the major install kit. Not replacing your bearings while you are installing new gears is just plain stupid. It would really suck to go in there and replace the gears and then 500 miles down the road a bearing goes bad and takes out your new gears. So now you have to replace your gears and bearings plus flush your housing. Do it right the first time. Also when you go to pull the bearings off the old pinion gear they normally get ruined. And when you try to get the bearings off the carrier to change the shims the same thing can happen.
Step up and buy the major install kit.