From what I have seen AC is making connections way too tight at YYZ. I have seen countless passengers arriving on International flights at T1 having a connection at T2 much less than two hours.
Considering the way that T1 is operating now... some flights at IFT, multiple flights arriving at same time without adequate ground crews and increased Canada/U.S. Customs processing times... the 1.5 hrs the original poster asked about is probably not going to be enough.
Best advice to better your chances, ride in comfort up front and take carry-on.