With that huge case, I would look at the new 230g Berger. It will likely give you better performance (wind deflection, retained velocity, flatter trajectory) at long range than the other bullets mentioned and likely be more consistent with the right powder and if you have enough barrel.
Shooting anything less than 200g at an absolute min. is a waste in a case that huge of a case. Most lr shooters think the thing the same for a RUM case and the 30-378 is much larger than a RUM case. The 30-378 is capable of so much more than pushing a little 180 or even 200g pill.
If you're not shooting lr, then nearly any bullet will do.