I am going to chime in with the others who have recommended getting in the night before and getting some rest.
Preaching to the choir here, but:
I do the YVR-YYZ redeye several times per year which has been the norm for me for the past 5 years. I've flown it in J; I've flown it in Y. I've done it after drinking too many glasses of crappy red wine in the MLL, or after not drinking at all. After sleeping in till 2pm, or after having been up since 6am after only sleeping for 3 hours the night before. Good rest on any of them? Not once.
I just don't find a 4.5 hour redeye long enough to get any valuable rest. Going somewhere for 9am after that flight is unpleasant. (I sometimes try to cab to my mom's and nap there for 2 hours first if I have the time

)
Also, if your potential new boss knows you're coming from YYJ, I can't really see how bringing small carry-on luggage with you to the interview would be a faux-pas... unless your carry-on is a SpongeBob suitcase or something. A second shirt is always useful. The one time you don't have an extra shirt will be the day a baby in the seat next to you decides to spitup on your shirt at 36,000 feet.