Nikko shotguns were made in the same Japanese factory as the older Winchester 101 that went out of production in the 80's not be be confused with the new 101 made in Belgium. An ejector for an older 101 should fit the Nikko.
I can't recall if these people still ship to Canada but they are the best source for 101 parts.
http://www.midwestgunworks.com/page/mgwi/ctgy/winchester-model-101-factory-parts
If you can't located a 101 ejector I'd suggest trying one from a Browning Citori. The guns are very similar in design and while I haven't tried it personally a Citori ejector might work in one.