Try enviro strip they bake paint off , dip in acid then dip in neutraliser and then dip the car in water to wash all the seams out etc , then fully prime the car in zinc coating. It's who fuzz Townsend uses on car sos and they do a lot of work for m sport to, around £1600 all in.
Or you could try retropower , they wet blast , fully dry car out , then they offer a hot galv coating that actually melts zinc in what looks like a blow torch on the end of a spray gun and is paint directly on to the bare metal.
The only major thing that would bother me about all of these companies apart from blasting is they would all strip the inside of the box sections etc far down the car like chassis rails etc , how does primer get back in again as I understand it's not like powder coating that electrically charged.
Surely it would be better to dip the car in primer even half way up so all rails etc are recoated and then spray the rest of the car in primer. The body shop could then smooth the dipped primer if there's any imperfections on the panels that would be seen on the outside of the car.

Cheers paul