That's amazing. That's way beyond panel replacement, that's closer to artwork in my opinion. Do you have any pictures of the work he did?
I have been doing metal work for a long time, and still don't know all that much compared to some of the guys out there.
If you want to see some amazing metal work go see what the guys at metalmeet.com are working on.
I have learned a lot from that site.
Also I was lucky to learn a lot from some great old timers.
Sorry but don't have pictures from that car as any I had disappeared. The big thing with working the metal is not to just pound out the dent but to try to undo the damage and work it from the direction the bend came from.
When doing section or panel replacement I always try to separate at the factory seam and put it back as close to factory as can be. I have a spot welder that I will use for all areas I can reach and the plug weld the rest.
If butt welding you can grind and finish both sides of the metal and make it look like it was always one piece. Backing the seam with copper helps things as it prevents blow through and it pulls excess heat from the surrounding metal.
Bob