RE: slug hunting
I'd use the rifled barrel. If it is the cantilver scope mount, go with a scope. If it has iron sights, try those and see if you shoot well enough at the ranges you'll hunt. You can try to mount a scope on the receiver of a pump gun. Some guys have luck and others don't. Be sure to tighten the barrel mounting nut as much as you can.
For ammo, go with a sabot slug in the rifled barrel.