Be careful not to configure the Benelli as a California-defined "Assault Weapon." That makes possession a felony. You'll do that if it has a folding or telescoping stock and a pistol grip.
You gotta register all firearms that you import within 60 days.
Be aware that unlicensed CCW and Carrying of a Loaded Handgun are both felonies if the handgun is not registered to you.
Keep in mind that California has two different definitions of when a firearm is "Loaded":
Under the general definition, a firearm is loaded whenever there is a round in the chamber, or in a magazine that is in the weapon. Ammunition attached the weapon in a way that it cannot be fired (like a shotgun butt-sleeve), or carried in the same container as the firearm do make it "Loaded."
Under the special definition, which only applies in specific locations, or under specific conditions, a firearm is "Loaded" whenever the firearm and ammunition are under the control of the same person.
California also has a statute that allows a LEO to inspect any firearm, in an area where shooting is prohibited, in order to determine if it is loaded. There is also California case law that allows a LEO to search vehicles for any such firearms based on probable cause.