I think you should be ok. After the extensive metal work on mine the number plates were pretty much going on another shell other than my original. There are "hidden" serial number stampings so if you want it "according to hoyle" you might want to re-stamp those, however, don't be surprised if they weren't stamped to begin with.
Here's a Willys thread eventually identifying the additional KFW number stamping locations. Unfortunately (it appears to me anyway)the poster that dug deep enough to find jakes old post linked the image to a defunct 3rd party site rather than a direct link here.
Here's a link to that thread
http://kfclub.com/forum/index.php/topic,10234.0.html, the clue the poster mentioned is the original document is another year back in jakes posts................... shouldn't be too hard to find........