Good choice. Just got back from our annual Nilgai hunt. Of the 10 hunters, 6 people killed 5 Nilgai bulls, 5 Nilgai cows, a Waterbuck bull, and a Waterbuck cow with .300WM. Ammo for 3 of them was Federal Terminal Ascent 200 grain, the others were using Choice Ammunition loadings with 180 grain Nosler Accubonds.

As far as anchoring them, you need to shoot them in the spine/neck/head to put them on the ground where they stand. Even a shot that does this to the heart will have your animal going 20-40 yards. That is the heart of the Waterbuck bull. He went 35 yards before dropping.

Any if the calibers you mentioned in your post works well, 300 Win Mag and up, Personally I would be mire focused on matching bullet with game. I just came back from Nilgai trip and used a berger elite hunter, but a A frame or bonded bullet would work fine. Personally I would never want a 26 inch barrel, but rather 22" easier to carry, manuver.

I’m a 30-06 fan for about everything. I’ve killed WT, mulies, hogs, elk and antelope with my Butchered Eddystone. Also Half a dozen animals in Africa. I hand load but essentially use the same bullet and load for most animals.

375 H&H just because it sounds cool.

Planned on buying ammo from Dallas Reloads. Figure 180 grn or 200 grn Accubond wish Partitions were available but no one seems to have those loads right now.

Debating dropping the rifle into a Boyd's stock but don't know, have no experience with that kind of thing. I'd really like it to weigh a little more to tame some recoil .