Ok turbo, slow down. I know exactly how green bearing work, which is why I don't run them. I run OE style, tapered bearings with adjusters on all of my cars and have adjusted end play on all of them. I am plenty aware of what can and can't be done with the adjusters.
The axle housing in question is an ORIGINAL A-body 8 3/4. There's nothing to indicate it was anything other than a factory axle, and nothing else from the factory is even close to the A-body width. Which means, it's an A-body axle. You have to realize then that means it came from the factory with tapered bearings and adjusters right? And that it worked just fine for decades with that set up before you decided it wouldn't work with tapered bearings?
The axle length was measured with a tape measure, which is a heck of a lot less accurate than the jigs the factory used. It's just a factory axle that's more than likely well within the factory tolerances.