I believe Remington had a 140 grain factory load for a while in the 1990's too...uncertain, though. What's availability for the ammo like in Australia, Kombi? I'm assuming pretty good.
I think you can take any comments about the .280 Remington as applying to the 7 X 64 Brenneke. I use a .280 and think it's one of the very best cartridges ever developed, and cetrtainly my absolute number one favourite.
In 1992 in Germany I saw a bunch of 7 X 64 chambered Rem 700 Mountain Rifles, with open sights, no less. I sure wish I'd coughed up the DM 770 (about $525.00) and bought one!