5k Epic > 2K output?

I have an Red Epic job with all but one shot being 5120x2700 and then one shot that is 2048x2700.

The director wants to render out at 2K and I just did a very quick test with the default 2k output setting in the config tab - obviously its probably not what I want to do but wanted to just get some advice before fiddling further and wasting any time. I believe he plans to have some letterboxing at 1.85? Not totally sure but will obviously discuss further when possible but want to know what to suggest for best output.

thank you
andrew