[Butch Cassidy Slept Here]

Wrong "V." I meant Varig, not Viasa. Anyway I note Varig does NOT offer service to Canada, except through code shares with Air Canada. Based on a quick look, I note Mexicana does offer connecting service Sao Paulo to Montreal via Mexico City. An "overnight," in Mexico City may be necessary. Service on Cubana (via Havana) seems to be available only from Buenos Aires.