Depending on the trade-off involved (cargo versus pax premium), might be better to route some of this excess cargo via YVR/YYZ B777's much bigger bellies.
Cargo is alway more profitable than Tango fares. If you are shipping full container or skids, shipping on routes with connections is always a problem. A lot of YVR -YUL flights are A320's, which can not carry wide body can's or any skids.