[Doe Eyes]

Boeing should have based the design on the newer 777 instead of the older (and smaller) 767.

The 777 is larger airframe than required for job.

Though I don't know, I expect the 767 avionics would be updated for this program, at least to the level of the 777.

[aviator]

The larger 777 can lift much more cargo and carry more passengers than the 767 and fly them to a farther destination. Much better for deployments when it counts. The avionics are close enough not to be a big factor.