Thanks for sharing the pictures of Dilly's rust bluing of the barrels. I hope that you enjoy the gun, and shoot it well.
I'm curious if you emailed AyA, and whether you got a response. Before the pandemic, Carmen at AyA answered fairly promptly, with date and model number from serial number supplied.
Of course, the date of manufacture and much more information is in the proofs on the action and barrel flats, and on the barrels just beyond the flats.
There will also be the bore diameters, choke diameters, and the weight of the barrel set at proof.
Despite the high price of a current AyA shotgun, the prices realized by older AyA shotguns are somewhat disappointing, particularly in 12 gauge with short barrels.
However, that makes them more attractive to those of us who appreciate and use such shotguns.