Well, several months too late I'm coming to the conclusion that I should probably be ordering some jets for my west coast US airline.
Both have similar availability dates.
The current DC-8 (-10) is slightly heavier and more expensive while holding less people. Its range is too short for transcons in factory config, but I assume with some biz seats we could make it from sea to shining sea.
The 707-120 is then clearly a better plane then the DC-8-10, but only slightly, and there are families to consider.
Is the DC-8-60 series inter-changeable with older modes (as far as route swapping?)
If I don't ever need any more than 2300 nm of range, how will subsequent models (707-320/720 v DC-8-20 through 55) stack up?