A wild boar has a thick gristle shield over the shoulders and front of the chest. The ribs are pretty close together. Therefore, a well-placed chest shot which does not destroy the shoulder meat is going to strike this cartilage or ribs, or both.
The 150-gr Remington RN bullets work well for me in the .270 Win.
The 180-gr RN Remington and Hornady bullets work well in the .308 and .30-06.
8x57 and 8x60S with 200-gr bullets are great - Nosler Partition and Speer GS at 2500 to 2600 fps will do it.
I love my Marlin .444 for stalking the big swamps. It swats.
But I am mostly stalking or ambushing from a blind, where I can be patient for a good angle on a stationary or feeding pig. On driven boar, and large ones, where ranges are going to be fairly close, I would go with something like the Speer Grand Slam, Trophy Bonded, or Swift A-Frame. I have loaded some Speer 160-gr Speer GS for my 7x64, and hope to get a boar with that, if there is any place left to hunt after all these forest fires, which just got corralled this week.