Roscoros, the most common or popular V8 petrol conversion in Oz is the LS2 6.0L Chev petrol V8 motor. The next would be the 5.7L V8 LS1 and then maybe the older 5.0L V8 as a third option. Companies like Marks 4WD Adaptors can provide complete kits or whatever elements of a kit you want to choose. Some gear is best sourced elsewhere for a better price.
But these places off the electrical integration kits you need as well as gearbox Adaptors, engine mounts, etc.
If you are contemplating doing it yourself, allow a budget of $10K as a starting point, despite what you may read elsewhere. This allows for a good running engine and the kit, exhaust, engineering, etc.
Good luck, keep us all posted as you go.
Cheers. Chris