Paul,
This has been discussed many times on the site. Do a search in the Modification Help board for V8 and see what you find.
Long story short is discuss with a competent engineer in your state to determine exactly what will be required before laying out a penny. Perhaps get in contact with "gp" on this site who might be able to put you onto one in Canberra.
You will need to do severe floor-pan mods to make that motor fit, as well as significant surgery in the steering department. In any case a small-block Chev is easier to fit (up to 307 is legal in NSW, don't know about ACT), because the shape of the motor is different - the Y-shape is thinner. Unless you've really got your heart set on the 308, I'd recommend you think about a Commodore V6 conversion, which can be bought off-the-shelf from Pat Gardiner at
http://www.v6conversions.com.auSpeaking as someone who learnt the hard way, if you're not in a position to do a significant amount of the work yourself, expect to spend a lot of money on this project. You will find a lot of people on this site will be able to give you good advice though, so you can avoid spending more money than you should.
cheers
RET