I have hunted pigs in S. Texas for a number of years. My preference when I started was the 45-70 in Marlin cowboy and a custom Siamese Mauser. I was trying to keep the loads for both down to a level that the Marlin could handle so as not to get different loads mixed up in the field. Then, on a whim I bought a Ruger 458 Win. Mag and decided to take it with on a trip to Texas. Loaded Down to about my max in the Siamese Mauser and had a ball with it.
Added a Winchester model 70 in .458 and have been taking both these guns, downloaded to top level II loads, really liked the Rem 405 grain soft point for this application but now as these are no longer available I'm using my cast bullets in this weight range and the Speer 400 grain soft point.
Funny thing, the rancher friend in S. Texas I hunt with mostly uses an old Winchester lever action in 30-30...it's old and beat up but I'd wager it has accounted for thousands of pigs.
You don't need all that much gun, just good shot placement.