Panel stiffness, Door metal thickness Options

[porschefile2010]

I wouldn't mind some input from the USA if possible.
Down here in NZ 914's are a rarety and my 75 2.0 is the only one I have really been close to and there are no others handy to check out.
I am bare metalling the car to go back to original- so paint strip, rust kill, etch prime etc.
I have noticed when I have been scraping the paint off the panels ( it's had three repaints)that the door panels have a hell of a lot of flex. The rear guards have a small amount, the fronts not too bad, but the doors! Are they all like this. There doesn't seem to be any side bars inside and they flex probably as much as 1/4 inch in the softest patches.
The doors are absolutely rust free and original paint right back to the first coats so it doesn't look like there has been any bodgy repairs.
So, question is this normal and if so filling and fairing must be tricky as it seems a difficult job bogging a flexi surface and then boarding it down to a fair surface?
Thanks

[Dave_Darling]

Early on in the 73 model year, all of the doors got reinforcing beams on the inside, just under the skin. They're heavy, but they are to help (a bit) with side intrusion into the car. Sometimes they get removed, but as they're welded in they do leave some evidence that they used to be there.

And sometimes someone swaps in an early-73 door because they're lighter while still having the later windows and window lifts.

--DD