I just have a few comments.

416-A or 416-8A was way before EV arrived, correct?
Unless I missed it, what is your method of measuring the parameters?
I have a procedure, but I'd have to dig through countless piles of paperwork to find it. Ok, here it is online:
Measuring Loudspeaker Driver Parameters
On stock altecs I've measured, they were within +/- 10% of spec, which is probably the norm given production tolerances. The measurement is touchy, especially Fs. I hang the speaker from the ceiling with chains.
Have you measured a stock good working unit to compare?

I'm wondering if GPA knows wether their magnatizer is even working? How does one measure the magnatization when done. Seems to me if it's busted, it could demag!

GPA did the first pair of 411-8A for me, and I measured the TS on the one good working one before sending them in. It was spot on, but the cone was sunk. when I got the reconed ones back, they measured like good 416-8B drivers......the parts used just weren't the same as the originals. Spider and surround were different. Of course, these are ferrite.

Bought GPA parts for a pair of 416-8C, had a local reconer install them, and they measured very close to spec. Another ferrite driver.

I also have GPA parts for a pair of 416-8B that I bought new, I want to recone these myself someday, but the parts are not dead nuts to the originals, so I wonder.....tha magnets should be good, they were never overheated, dropped or abused.

Ron