YYZ-CDG is not a 777HD, it's a regular 77W.

But I would otherwise concur with vernonc's comments. If it's really important to you, pay the $90 and be done with it. You'll have certainty that you'll have a window and more room overall.

If you want to chance it, one thing you might want to do is look up buying a new ticket on the website and checking the seat availability after selecting a Latitude fare. You will notice that it shows a much larger number of available seats than if you preview seat availability after selecting Tango or Flex. Example: looking at AC880 on the 29th with Flex fare shows only preferred window seats. Looking at it with Latitude fare shows a bunch of non-preferred window seats towards the front of Y.

If the window seats all show blocked out, even when previewing using Latitude fare, they're probably all assigned already and you should just pay the fee. If you see lots of availability when previewing with Latitude, you may have a decent chance at snagging one at check-in, especially if you check in online 24 hours ahead.

But the only way to be sure of getting the window is to pay the fee. Up to you to weigh the risk/reward tradeoff.