Any script to 'fix' normals/winding order?

This will flip the triangles. I'll leave it to you to pick one and compare the normals and fix them they way you want.

 @MenuItem("GameObject/Flip Mesh", false, 4) 
 static function FlipMesh() 
 { 
     Undo.RegisterSceneUndo ("Flip Mesh");
     var trs = Selection.GetTransforms (SelectionMode.Deep);
     for (var tr in trs) 
     {
         var r : MeshFilter = tr.gameObject.GetComponent.<MeshFilter>();
         if (r)
         {
             var m : Mesh = r.sharedMesh;
             if (m)
             {
                 var tris : int[] = m.triangles;
                 for (var i : int = 0; i< tris.Length; i+= 3)
                 {
                     var t : int = tris[i];
                     tris[i] = tris[i+1];
                     tris[i+1] = t;
                 }
                 m.triangles = tris;
             }
         }
     } 
 }