"and there is no .277 equivalent of the 175gr .284 partition because it wouldn't stabilize in the slower twist .270." There's the 180 grain Woodleigh that will stabilise in a 10 twist barrel.
That bullet is not reliably stable in the 1:10" twist 270win. It'll do better in the magnums, and of course in low pressure (hot or high) air it will do better.
But marginally stable bullets like that can become inaccurate or outright tumble at distance, sometimes without much of an understandable pattern. They also experience extra drag due to wobble in flight. There are reason long range rifles are adequately twisted to fully stabilize the bullet used.
It has a lot of potential as a 27 Nosler bullet though, which is interesting since it predates the 27 Nosler.
