I have a Plan B; take the VIA Rail service to Toronto Union Station which leaves before 2 pm and arrives around 7 pm. There is a 7:43 pm GO commuter train that leaves Union Station on the Lakeshore West line and can get me to Burlington station near Hamilton, where I can get a scheduled bus to Niagara Falls. I can then walk over the Rainbow Bridge, clear CBP, and get a scheduled bus to Buffalo five blocks east of the checkpoint that leaves at 2309, getting to Buffalo around midnight. A taxi takes 20 minutes to get to Depew station. The Lake Shore Limited leaves at 0039.

Or I could just overnight in Montreal, and then see what my options are in the morning. If the Ocean runs late, this is what I am thinking about doing anyway.