Personally, I would build a .28 Nosler (WAY better barrel life), especially if you want this for target shooting, and not just strictly for hunting...
Regardless, I would go as long as you can handle. If you're not planning on toting the rifle a lot and you want it for LR shooting and hunting, and it will live its life on sandbags or a bipod, then I would go with a 28" fluted Sendero contour, that extra weight will be beneficial for LR shooting.