BMIC,
My understanding is you want to try to have an even amount of shims at the top and the bottom. You are simply shimming to maintain a proprer preload.
I believe all Willys will vary a bit on the amount of shimming required, but I checked mine and found .020 shims on top and bottom.
You can put a bit of sealant on the shims. Not much, or it will mess up your preload. I do leak a bit around the studs. A little Permatex #2 on the threads may help stop this potential leak point.
Tim