"...who knows who has replaced a voice coil???"
Back in the day: we reconers were buying our parts from Waldom Electronics*. All of their voice coils were wound with round, copper wire and they carried parts to recone virtually anything commonly manufactured.
If their catalog/parts list didn't have an exact reference, via the speaker's ID numbers: they could be sized and estimated, to fit and function.
In either case: very seldom exactly to original specs or T/S parameters.
At the VC and cone junction: EV always used epoxy, which can't be dissolved, chemically. That would require a reconer to replace everything, to change the VC, which should be easy to spot. If you're familiar with the original EV components, that is.
Old as the systems/components you mention are: anything's possible!
*That's: IF a customer wanted to go the cheap route and not buy an OEM reconing kit, from the likes of JBL, Cetec GAUSS, Altec, etc, which COULD get pricey.