Yes SQ flew both the B743 and B744 into YVR in the late 90's , early 2000. Then switched to A340 when that aircraft came into the fleet. SQ did not enjoy the loads between Seoul - Canada as it does now. Hence the eventual downgrading of aircraft size.
Now as most transpacific thin routes are operated by 2 class B777-200ERs, the SIN-ICN-YVR route has this aircraft type too.