I have killed them with a 22 mag but it is not my caliber of choice. mainly use a 41 mag, 35 rem, 243 or 308.
the 7.62x39 is a good hog caliber. good luck and let us know when the BBQ is ready.
I would pick the 6mm hands down between the two choices you gave. You can kill just about anything with a 7.62X39 but the 6mm is one of the best deer/Hog rounds ever made. It is far, far better than the 7.62X39 Not even a comparison. In my opinion.
I have killed alot of hogs with the 223 and 22-250. The 6mm should be plenty. I usually aim just behind the ear. Almost all of them go straight down! Good Luck.
"I realize neither are first rate, but which would you choose?"
I do a lot of hog hunting and the calibers you have are more then adequate. I almost bought a CZ 527 Carbine in 7.62x39 for a new hog gun. Great rifle.