Some well intended advice above. Unfortunately though some is inaccurate.
The agreement with the FAA excludes you if your FAA licence was based on another foreign licence. Check here:
Conversion agreement between U.S. and Canadian officials - Transport Canada
Look under the 'agreement' for 2.2 Eligibility.
Also, the flight test for the ATPL can be done on a full flight simulator (even initial). Check under 'Aircraft and Equipment Requirements' in the IR flight test guide here:
TP 9939E - Flight Test Guide - Instrument Rating - Transport Canada
A type rated approved check pilot can do the initial IR flight test in the sim.
Good luck.