A 45-70 is plenty of gun for hogs.
I've killed them with a .308, a 5.56 mm, a .357 mag, and even a .22 lr (young shoats).
Feral hogs can run as large as 400+ lbs, but typical size where I hunt in Central and South Texas is about 120 - 200 lbs. As they are not a native game animal, there is no season and no limit.
Javalina are much smaller (40 lbs or so), and are governed as a game animal.