Re: cj6 questions
Don't jump to convert the thing to a v8. I'd look at the buick v6, either the 225 or the 231. The 225 has a heavy flywheel and is a good off road engine. A friend has a 67 cj5, and the 225 makes plenty of power. You can also get them cheap if you look carefully. You could find a tranny that will bolt to the dana 18. The dana 18 is plenty strong enough for these engines, and they won't require frame beefing. The gear splitting with the overdrive in the 18(if you have it) is pretty cool. It also makes a 3 spd like a 4spd if you shift 1L, 2L, 3L,3H.
Do replace the axles, though. Tires of any size will put a hurt on the old relics, eventually.