Easiest to fit the same again, if you fit others then you will also need to replace ECU, most likely also wiring loom.
If you only change block like for like and leave old ECU in place it will just run (possibly will require teaching it injector values etc) but you won't need to reprogram immobiliser (already fairly tricky on a mk6 and highly likely means you will need to get new transponders for the keys too).
Out of interest what's gone on your CCZ?
