84xxx is the exact range where we see version 1 of the screwback Autavia case switching over to version 2. We have several 843xx watches with the earlier case but an 844xx with the later version.

And as you say, it aesthetically looks better in that case plus the ring of visible metal outside the dial on the watch David shows looks much more to me like a second version case.

So whilst the serial number isn't conclusive as it's in an intermediate range, I still lean towards the version 2 case as being the more likely for this model. I wonder in fact whether it being intermediate is significant - a new dial to help herald in a slightly changed case shape? Doesn't seem at all out of the question to me.