Changing the default distance measurement to km instead of cm?

For a project I’m converting to UE4 I want to change the default world size to km instead of cm, while still being the same scaling wise. Ideally I’d want to be able to do this per-level if possible instead of per project (some levels are indoors, some outdoors). This is purely visual, I don’t mean the Editor Appearance thing which also changes how it translates to Unreal Units - I just want to change what is displayed there.

Is this possible?