Seems to be an updated version of quenching- spot heating with an oxy then quenching with a soaked rag to shrink the metal- had to do that with the full length of the rear quarter  of the RS to get the body line back again. The  skin looked like it had cellulite and had been covered by a huge sheet of bog instead of being panel beaten.

Deano said:
"The only thing I miss with not having an oxy, is being able to do heat shrinks."
No need for an oxy to heat shrink.
Try a hand held disposable propane burner available from most hardware stores. The kits have a heating tip included.
I have successfully shrunk many large panels over the years using the burner and a wet rag and good hammers.
The propane burner can in many cases be a better solution than the oxy because the heat is much softer and the heating area is larger than the oxy tip. As always experiment first.

Quenching after applying heat is not the correct way to do it.  Heat until red about size of 5c piece, hammer/dolly and leave to cool on its own.  This way the metal doesn't harden and can still be metal finished.

"This way the metal doesn't harden and can still be metal finished."
The annealing process (mild heating with no quenching) is the final step after the shape has been restored.
I avoid heating past light blue.
But we each have our own ways of doing things.  :)