^You are a brave man, braver than I am, certainly. If I had a fight like that with a 75-pound pygmy pig, I would certainly be very chary of tackling even an average-size 160-pounder, much less a big, ugly old 250- or 300-pounder, even with a proper boar spear with a crossbar like the one you show (Cold Steel?). In reality, of course, I am much too old for such undertakings these days.
I am assuming that your brother uses some pretty peppy .45 Colt handloads in his Henry Big Boy. Based on my own experience and observations, I don't think much of using magnum revolver cartridges on wild pigs. I have seen some pretty sorry performances, even from a .454 Casull and heard of many more.
sorry, he uses the .44 magnum razorback XT . 225gr @ 1300 fps
Here is a link -
PS- He drops pigs and he is not a great shot, haha