Hello JakeH,
Personally, I favor a bit "more gun" than some folks do.
Nonetheless, the .270 Winchester / 150 gr Nosler Partition would be IMO, a pretty good combination for non-dangerous game, such as you intend to hunt.
I no longer own a .270, (instead now favoring the .30-06 but that is one of my many character flaws, not yours, haha).
Anyway, in the past I have hunted here in Alaska with one and found that 150 grain soft points, virtually always pass clear through both deer and caribou on broadside shots.
Even softer ones than the Nosler (150 gr Hornady spire point) passed clear through but, 130 grainers typically did not pass through large bull caribou.
The old NP is somewhat misunderstood in these super tough, premium bullet times we're definitely enjoying today.
The NP was not intended to give the "perfect mushroom" except at low velocity, (such as for longer shots on game animals).
Even though I believe the Swift A-Frame is the very best of the best premium soft nosed bullets available nowadays, I do like the Nosler Partition and have hunted non-dangerous game with it in Alaska, (more than one caliber rifles) as well as in Africa for so called plains with the .375 / 300 gr NP.
The NP has always worked perfectly for me, according to what it was designed to do, IE: The front end deforms violently on impact, even flying apart if striking at high velocity, and tail end holds together then, drilling a deep path through the vitals and usually out the other side of the animal - blood out, air in).
All that being said, conversely if I was to hunt buffalo with a .375 H&H (is there any other kind of .375? lol), I would definitely not choose the NP for my all important first shot.
For that, I'd definitely want a 300 grain A-Frame.
However in the first place, I'd want to use a .40 or more to hunt buffalo with anyway, (because I'm an OCD weirdo).
Parting Shot, as it were;
If you cannot find factory loaded (Federal brand) Swift A-Frame bullets for your .270, just continue on with your 150 grain Nosler Partitions and I predict you will have a wonderful hunting trip to Africa with a lot of happy surprises and no unhappy ones.
Cheers,
Velo Dog.