Your question is a bit confusing Geniel, because the Ford Focus wasn’t released in Australia until September 2002. Which is to say, there wouldn’t be any 2000 model-year Focus engines lying around waiting to be fitted to another Focus. However, the original Focus was launched in Europe in 1998 and that car was broadly the same structurally as the version sold right up to 2005 in Australia.
The catch, of course, is that the Focus was sold with both a 1.8 and a 2.0-litre engine here, so you’d need to make sure that you were trying to fit exactly the same engine in exactly the same specification to ensure that everything from the fuel lines to the wiring loom and the cooling system to the gearbox matched up and fitted properly.
If, by some chance, you’ve found an imported Focus engine, be very wary of fitting that as it may not have the appropriate pollution equipment fitted to be legally registered in Australia. And don’t forget, whenever you swap an engine you need to inform the registration authorities and your insurance company of the new engine number.