Not adding much here but just throwing in. You can go to hevi shot 3" #7 or Federal HW #7 and just about any full / extra full choke and have a smoking little gun. The shells will make a huge difference. And believe me, those HTL in #7 will do the job.
If you decide on a choke, Pure Gold, Indian Creek or Sumtoy are all very, very good. I mite suggest something in .570 instead of .555 range. It will open up a bit at and make it a little forgiving. A surprise low cost choke that shot very good in my tests was the HS Strut extra full Turkey choke. I got it on sale for $12! It wasn't quite as good as the ones I listed earlier but still at 40 yds it was throwing 120's in 9" circle at 40 yds with a good spread. Very dead turkeys either way.
I set up a Mossburg Bantam 20 with a Pure Gold .570 and shoot the Fed's #7 for my Dad and it is a solid little gun. In my little H&R with the Pure gold it likes the hevi 13's better.