If youre taking an efi xr3i engine out take the head off and its the same as the fiesta rs turbo one so you can use your inlet although the injectors and i'd imagine the throtal body are differant.
From what ive been told the internals are the same between the escort and fiesta you just need the hole for the crank position senser which you can have put into an escort block there was a tread some time ago where some one had made a template for the hole position i cant remember who it was though try doing a search for it.
hope that helps mark.