You will always clear customs on your first entry point to Canada. That will be Toronto for you. Even if you happen to get in right after a very large plane of people who all need a lot of customs attention, you won't wait more than 30 minutes in line for customs. I think a two hour connection will be fine. You almost certainly don't have a terminal change (that would be likely only with an airline change) so once through customs things will go pretty quickly for you.
As always a vital piece of information is whether it's all booked as one ticket. When it is, you know that
- the airline thinks that's a reasonable connection time
- if your incoming flight is late and you miss your connection, the airline will take care of you. Which might mean you read your book for a few more hours than you wanted, but you won't have to shell out for a replacement plane ticket or the like
I rarely connect in Toronto (I believe I've done it exactly once and that was domestic to domestic) but I land in it all the time, and leave from it all the time, and since you need to clear customs that's essentially what you are doing. Two hours will be more than enough. Even if your incoming flight is up to 30 minutes late you may fret, but you will make you connection.
Enjoy Sudbury! Hope it's a little warmer by the time you get there! If you're leaving this week, pack warm!