You live in Naperville? You can sell a Chicago resident any firearm you legally own there. Period. It's up to them to know and follow the Chicago municipal laws.
But just to make you feel better, I don't think they have any laws regulating pump shotguns as long as the owner registers the firearm before bringing it into the city.
Again, as long as you follow the law with your sale (fill out forms per FOID act), then it's up to the seller to follow the law after the sale.