Think you answered your own question. "Where to get the plane"?? The
777-300's are/were used in the absence of an available 777-200. The 5th 772 was just recently delivered and undergoing pre-service modifications before it enters service. Utilizing the 773 on either YVR-SYD or YYZ-HKG activates a load restriction of approximately 80 seats. I think the first priority is to remove all reamining 343's from service and replace those flights (namely YVR/HKG/YVR) with 777's. Based on prevailing loads, it would appear that the route is ripe for another frequency.