Resonably easy swap, except it seems to require a number of off the shelf (at least in the UK) but expensive parts to make it all go.
This or Pinto should be easy enough, Pinto you probably should upgrade at least the front suspension as it is a heavier engine. You could also forgo the gearbox for now, less of an option if going to a different engine. Also avoid the DOHC "Pinto" from late model Sierra's, they are quite a differnt engine with little option to improve from standard.
What engine does your Escort currently have? If already a 1600 then you can do a fair bit to make them go betterer, same for 1300 to a lesser degree.
What model? If low spec you may have front drum brakes that probably should be improved before swapping any engine.
Diff ratio might also be a consideration but this should be easy enough to swap if need be.
