I would suggest getting a Remington 870with arifled barrel and cantilever scope mount. As far as a scope, I would mount a Nikon 'Prostaff' 2-7 x 32mm shot gun scope. Ammo - Hornady SST sabots.

I like the idea of having a pump action for quick follow-up shots if nessesary in lieu of a single shot.

Attached is a photo of this same set-up next toa 200 pound doe I shot through the heart at 110 yards.

http://i243.photobucket.com/albums/ff75/huntingthenorth/P1010002.jpg