IF one were to "dip" this car, to remove rust......how much would be left to rebuild?????
IMHO, anyone who buys this car for over scrap value (or over 5 figures) is out of their mind. The ZF would need to have just about every gear replaced, as anything not immersed in 90W is ultimately junk. Same for the engine......sleeves could be used...... I love the 2V intake and carb!
All of the switches and gauges are certainly piles of oxide on the inside....
About all that I see as worthy....are the windows, window frames (brass?), anything alloy or magnesium has a small chance..... and thick cast iron...seat buckets might be OK,
Every picture that you look at just reveals surface after surface after surface which needs to be cut away and replaced! The frame rails are already made of tin foil......now there is little left of that but for a scaly rust surface of ferrous oxide that will shatter in to a pile of "crunchy" when disturbed..... I grew up with "disappearing" cars.......slowly being eaten by metal worms........ holes in the floor that you can see the road pass by underneath....... Just say no! 
It would be far easier just to start with a blank pallet of flat steel, and build a Goose from the ground up! There would be far less crap on your floor!! )) ....and less feeling of despair!
Again, just my humble opinion. Not for me.....