I'd stick with the good modern shotguns - benelli, beretta, browning, winchester, or remington. Go see which one fits you best.
Check how they mount and swing for you. You might find one that fits better than the others. Many now have the shims to adjust how the stock will fit you - consider that aspect too.
Mine are all 28 inch barrels (11-87, beretta 302, and beretta 390 extrema). A 26 inch tube will shorter you gun up a bit, but not by much.
3.5 inch gun do have longer receivers, but you might not even notice that. I shoot only 3 inch out of my 12 gauges, but then again, I do shoot an SP-10 quite a bit too.
Sporting clays and duck shooting require shotguns that swing well. Check that aspect too.
As for Browning Auto-5s - they were a good gun in their day, and still are. But the newest one might be 30 years old, and aren't as easy to take down as the ones listed above.