Darren,
Why don't you just email Rick Craig and have him post you some?
I have some 6 ga. philips pan heads that I could send you, but most are only 3/4. in long (that'd be 18mm), and I think they'd be too short. I have a few that are 25mm long, but I only have 5 or 6 of these.
Painting and ink look nice until you touch the slots with a screwdriver.
If Rick can't supply you with some screws, and you have to get them from the US, try Mcfeeleys square drive screws -
www.mcfeelys.com - for the best in driver mounting screws. Of course you'd then have to get a square drive screwdriver, and I can't remember seeing them in Bunnings because I never looked.
Frankly, you can't get anything in Australia, it's a lost cause! Pity
Steve