It will recognize the key providing you keep the same ECU.

But personally, don't bother, as a point of trivia the 1.25 is as powerful as the 1.4, the latter was more powerful but was de-tuned for emissions purposes.

They are indeed the same engine, that being the Zetec SE, just larger in displacement, as is the 1600 engine fitted to the Zetec S and Focus etc.

It will be cheaper and easier to buy something more powerful outright.

Martin