Zetec-SE Sigma 1995–present
1.25 L (1242 cc)
1.4 L (1388 cc)
1.6 L (1596 cc)
1.7 L (1679 cc)

You want the 1.6 out the focus, as far as i'm aware there is little difference in the actual engine between the Focus and say the Fiesta Zetec-S, the power difference is down to the ECU/Induction etc...

The only other option I can think of is going to ford and asking them to cross ref your vin plate?