Just aluminium pop rivets mate. Thats why I used 10 per side. If you used a higher grade of rivet you could safely drop that back. I didnt think it will be a problem.
The fan is precisely the same width as the radiator. Its off one of our own Aussie models, a Holden V6 Commodore model VS. So I dont think you guys will have much luck finding one...lol
You may find that Buicks with the 3.8 litre V6 (same engine as the commodore) may be similar (guessing).
Good luck.