Noting the similarity of that giant pie in the sky Airfix kit to one or 2 Chinese designs, could I proffer that in spite of the derision Chinese strategy tends to attract, its actually not a terribly bad idea to accost proven designs and reap the benefits at reduced cost and risk.
Is there therefore not an argument for some consortium buying up the YF-23 plans and just building that instead? Obviously with a relevant software upgrade amongst other minor mods as appropriate.
Have we not now reached the stage that certainly UK Plc should start asking itself, just how good does this thing actually have to be, if the development costs and vulnerability to cancellation actually mean we would only ever end up with a handful, if any? Quantity has a quality of its own after all.
If you built an updated YF-23 you might even find you had the US as a potential customer.
Just my tuppenceworth
Cooch