Daveo,
As for factory loads, you can't do much better than the 150 Noslers Partitions and 150 Swift-A-Frames you mentioned (although I must admit that I did not know that someone made the A-frames in the 270 Wby Mag).
The only other factory ammo that I would recommend is Weatherby's 140 Barnes X, and Federal's Premium Trophy Bonded which, I think, is available either in 140 or 150 grain.
It's a shame no one makes 160 grain ammo for the 270 Wby because its sectional density would be great.
Zachary