If you just have carryon, you should be OK but it is tight.

If you are seated in the front cabin, it is a lot easier to get to the front of the line at Canadian customs as you are in the first group off the plane. If you are at the back of the plane, then you have to really hustle to get ahead of the crowd.

Yours is the first arriving flight in the AM. If you are on time (or preferably ahead of schedule), then you might not have other planes inbound from the USA to compete with. Unfortunately, they get the westerly winds and are more often ahead of sched than the westbound planes.

From one of my pre 9/11 posts:

"I have done the reverse; half hour connect from T1 (including clearing immigration) arriving from MEX to T2 transferring to YYC.
I was first off the plane (being up front of course) and there were no line ups in immigration or at security in the tunnel. I ran to T2 in the tunnel.

I made it with 5 minutes to spare and fortunately, they found a business class seat for me. Then the plane left 10 minutes late so I had "a bit" of breathing room.

Not recommended for those out of training though!!!! "

With US preclearance, you might need a good half hour just for that. Taking the shuttle bus from T1 to T2 shortens the walk considerably.