My first double rifle, a .450-3 1/4" N.E., was built on a 16 bore shotgun almost identical to the one you have pictured. It has over 1000 rounds through it and is still going strong and tight. The main issue with the that cartridge in a 16 bore, is that it is a bit light, making the recoil a bit sharper - it only weighs about 9.5 lbs. , should be 10 lbs. For the larger rimmed cartridges a 16 borea bit small and you begin to push the limit chamber wall thickness and breech area. Also, because of the larger bore sizes, it is even harder to keep the weight up where it needs to be.

The AYA should do everything that you want and allow the weight to be pushed up to what it needs to be.

Ellis