Hi. Pumas and fiestas have airflow meters! The physical fitment of the engine should be easy enough, wiring wise may be different. The nice thing about doing this to a zs is that they have the same fuse box as a puma...meaning the puma harness and ecu plug straight in. Not too sure about the focus wiring tbh...

I'm someone can advise... A 2.0 might be a better choice though...focus to focus conversion will be easier!!