Can you recommend something suitable?
You do the right thing by giving your expensive hand-built Browning a rest and buying a semi-auto to take wildfowling instead.
I dread to think what a new set of B2G barrels would cost if the originals had to be replaced!
The new generation of semi-autos out there have been specifically designed to handle steel shot cartridges (at a tenth of the cost of your O/U by the way) and a number are now made with 3.1/2in chambers to fire super heavy 12-bore goose loads, so you are really spoilt for choice.
It would be unfair of me to recommend any particular gun because most manufacturers make excellent semi-autos.
However, many come with slightly shorter stocks than the standard wood found on an O/U so it might be worth picking one that offers a choice of butt pad thicknesses allowing you to make it as close a fit to your Browning as possible.
And it?s likely the cast and comb height will be different, too. Some makers have addressed this problem by supplying shims that fit between the stock and receiver so that the new owner can alter these two important measurements to suit as well.
Your best bet is to look closely at all the guns, then pick the semi-auto that offers you most options.