While NEF does have a barrel accessory progam they don't ship to Canada.
I have heard talk that you can buy a used barrel of a private individual and ship it accross the border but I really don't know the legalities of that. From a Canada customs point of view it is a no brainer it is just a barrel you can buy it without paperwork, but I think the seller is the one at risk from his own laws and I do not understand those.
NEF recommends factory fitting only and if you don't know what your doing there right, but there are guys state side that swap barrels all the time but it is a crap shoot wheather that barrel can be made to work on your frame.
Go to
www.graybeardoutdoors.com there is a really active handi group there, lost of good info.
Between tha hassle getting it and the risk it will not work we are better off buying a new gun and atleast with a handi it will not break the bank.