Based on your criteria, the 11-87 Police model is the way to go for you..or if you could consider a pump, get one of those remington 870 marine magnums.
It is set up to use 23/4 or 3 inch magnum shells, takes 8 rounds, is finished to retard corrosion of you are shooting it in the rain and most of them now seem to have ghost ring sights. This is good if you plan to use slugs and expect to hit anything with them past 40 yards distance.
I also like the saiga 12 someone mentioned, and you can trick it out to look and handle just like a Kalashnikov. Check out www.warriortalk.com for a subforum on the saiga shotguns.
Many thanks, all.
I’ve printed-out your replies and am visiting the links, and printing-outall of them, and using those which my local armorer thinks would be worth investigating.
Of course, he’s got some of those in-stock, and some which weren’t mentioned, and I’ll be evaluating them, too.
So many choices; so little time.
Again, thanks for pointing me in the right direction for my choice and decision.