Good story! Congrats on your kill.
Those pigs will breed like rabbits, given half a chance. Hope you get a handle on 'em before the whole area is covered up with wild pigs.
I can't tell anything about the wood grain from your photo, but the rule is to always back the bow if there is any doubt about the grain. Sinew is best, but thin rawhide would be good too. I've got a bow I backed with raw linen cloth that is still holding together. Of course, I hated the white color. Using acrylic paints, I painted a diamond pattern on the limbs. Green background with yellow and red diamonds. It's remarkable how well it blends in with foliage.
I've got some raw silk cloth to use on my next bow.