Boeing (and BAE as a sub? They seem to have some play in this) seems to be building the aircraft with a modular methodology, so that you could customize the design to meet UK-unique requirements.
(No, I don't work for, and don't own stock in, Boeing.)
I think as a nation we've already been there and tried that only with slight role reversal.
That didn't work out too well for neither party although Boeing managed to walk away with what is essentially their Mission System funded by the UK taxpayer
