Few questions why 3.5" round - really not needed stick with 3 inch
Why new gun - have you thought about buying a second 11-87 barrel. I did - bought a cantelever 20" for my 11-87 and topped it off with a Nikon Mondarch Turkey Pro scope.
Barrel came with a rifled choke tube to which I just added Hastings Extra Full 0.665 to it and was done.
Just an idea.
JW