US to International Transit at YVR

[pilot]

Didn't get someone familiar enough over at UA Forum (http://www.flyertalk.com/forum/showthread.php?t=859307) to provide an answer, so I'll try here.

I'm looking to book a UA award on a Thursday in October that connects in YVR: UA SFO-YVR, AC YVR-HKG. I just want to know how safe it is.

UA arrives at 1255, AC departs at 1425. YVR's website says I have to go through Canada immigration and customs. Is this the full procedure? Or is US-international transit a separate and/or quicker line?

FlightStats shows the UA flight being 40% on time and delayed 30 minutes on average. 90-30=60 minutes sounds tight as I recall my last experience entering Canada at YVR. And I wonder if the stats improve significantly after the summer travel season?

Don't mind if I absolutely have to be stuck one day in and around Richmond/Vancouver, but I just hate to barely miss the flight.