I have couple of hints for your consideration:
- a spare part kit might be an good idea, either fitted or unfitted. Tumblers with firing pins and all the springs are worth of thinking. In 2002 I ordered unfitted spares to my wife´s AyA#2 for the cost of 45eur (see the photo, firing pin returning springs are missing from the photo). If spares are unfitted, gunsmith services are required when replacing them.
- ask AyA to send you photos of the available stockblanks of which you can choose.
- perhaps you already know this page where you can find AyA exploded wiev dwgs and spare part prices in Scotland:
http://www.chambersgunmakers.co.uk/AYA%20shotguns.htm