Streets to answer your question, which I'm sure you allready know. If it's a doublewall water should not be able to get to it.
This is probably protected enough from the elements. On the other hand if you are not sure if the elements can get to it, You could weld any holes that you may have drilled to use a slap hammer to pull the dents out with. I did this to my 73 mavrick.
Lots of fun getting the shape right. Had to go over it about six times. Are you testing me buddy. HE! HE!HE!


~ Vegas ~