I used to own a 20-bore 117 (detachable seven pin sidelocks, third fastener as described above)

It was a great shooting shotgun - and it handled nicely.
The barrels weren't struck as nicely as a Brit gun, the wood wasn't finished like a Brit gun, but it was a really good sidelock ejector gun that I didn't have to think about screwing up in the field.
Sold it to fund something else...

Armbar - take advantage of that cost/condition metric.
I got my AYA at a good price - and didn't lose money when I sold it.
Before you buy, handle and shoot one if you get the chance.
Make sure whatever you're looking at has the (otherwise indescribable) 'Quailish' quality that you want.

Cheers
Tinker