Thanks for all the comments guys

Been busy again on the body. 

I went to work with my dremel thinning from behind and then picking rust holes through particularly at the bottoms of the doors and the wheel arches.

Once this was done I airbrushed various browns as a rust layer and then went to work with the salt and water!  I find that to avoid blowing the salt off when airbrushing with the salt technique that its best to get the salt on and then leave overnight to  fully dry out.  When spraying the next day no salt comes off!

Then a blast over with white and a little red for the fins (you do get decals for the fins, but I went with spraying) Once this was dried I washed off the salt

After this I touched up the paint in various ares, painted in the chrome and did a door line wash.  Then a quick seal with gloss and I added all the decals.  I will rust over the decals where appropriate later, then another seal with gloss.

Next I started on the base.

I want to show this in a New York alleyway having been left to rot so using some foamboard I made a design with part of the wall being brick with a bricked up doorway and on the other side I used wall filler to create a rendered wall.

Thanks for looking!