Is this a driven hunt, or hunting from a stand? It makes a difference. With pigs, draw a line between the eyes and the point of the shoulder. Any hit along that line will anchor your boar without difficulty. If you hit the pig behind the shoulder, the pig will run, even with a perfect double lung hit, no matter the caliber. The distance will depend on the lethality of the hit.
The .270 is more than sufficient with a quality bullet, but the larger calibers put larger holes on running pigs. On a standing pig, caliber makes little difference with decent shooting.
The following pig was hammered with a 300 grain .416 tsx moving 2800 fps mv and still made it about 75 yards. Of course, a blind man could have followed the blood trail to the downed porker.
416 hog