Can a AU XR8 engine fit in my EB V8?
And has anyone done it before?

The engine yes they are basically the same engine..
Where there would be issues is running DIS system with coil packs etc..
Just swap over the dizzy from E.B and your fine..
If you want to keep strong spark?
Then fit the crane ignition box..
Some maf, intake senser and TPS connectors are different but easy to get around..

As well as the engine what elese what i need (getting a AU xr8 engine)
1.Extractors
2.have a throttle body for a xr8
3.????
could i use the same alternator?, power-steering pump? Fuel pump? Injector conections?