From the title, it seems like you are asking about European bumpers. MK1 will fit, but since it is somewhat thinner than its NA counter-part (2.5 mph vs 5 mph), you will have to remove the foam and modify the steel bar. The bumper from MK2 will not fit because it is a completely different model that doesn't resemble good ol' Focus at all.
P.S. Just in case you really do it, let me know where I can take a glimpse at your motor [thumb] So far, in Sacramento I have only seen chav-moded Foci, nothing worth of attention.