The shield on a boar hog is not from fighting.
If you castrate a boar hog, the shield will slowly go away, the shield is caused by hormones in the hog.
Contact the outfitter you are going with and ask him what you asked here. He knows what works the best where he hunts.
Have your read on www.texasboars.com?
Go there and read about the anatomy of hogs, it's different than deer.
I shoot a lot of hogs with a .222 as that is what I carry for a truck gun. Some consider the .222 a bit light.
If you watch hogs, they constantly moving, they do not stand around as deer do. Body shots work much better.