If you were to buy a New Turkey Gun

[3" 870 Shell Shucker]

I would put a hevi-13 #7  shell in the chamber

YES.  Or 6's if I couldn't find 7's.  Almost any Full Choke, Extra Full Choke, or Turkey Choke will kill well at 40+ with Hevi13.  Go for the H13 shells.

[Gobbling Buck]

Choke....but #2 would be a scope.

[joshua]

Aftermarket tube.  A bead will do just fine if the choke can get the pattern there.

X2