So you want an economical bird gun, and you are a big guy.
With economical guns you might have to do your own stock
fitting and you might also want to get the cheap trigger worked
on. If you can do that then a Mossberg 500 is just the ticket.

You don't want a pump though, you said. So SuperXone
gives you an answer. You still might have to fool with the
trigger if you are finicky and you might have to fool with
the stock to get it to fit.

On the other hand you could hunt with your clays gun,
and not have to do any more acquiring, modifying, and
fixing, just take what you have and use it. That makes
the most sense, but people don't often make sense,
so the answer is still open.