quote:it seem like they neutralize the car with a good pressure wash. then treat it with some kind of chemical that prevent surface rust.
All liquids.
Please, I strongly suggest you find a method to have that shell baked in an oven to force out all the hidden fluids.
My initial cautions have been supported by several others comments.
I would hate to read about your paint job, or rust prevention, failures several years down the road after your restoration is finished.
To paraphrase a Pantera buzz-word - BAKE IT!!
Larry