Personally, I would MUCH rather start with a 2WD that hasn't been butchered or abused than somebody else's abortion on wheels, which is what that first truck is. 127,000 miles is VERY low miles for an 80s vintage Comanche. The ad says "OBO," so offer him maybe $1000 or $1200 and see what happens.
Converting to 4WD is a bit of work, but the parts can all be gotten from a Cherokee in the junkyard. The only thing that doesn't swap over directly is the rear driveshaft, because of the difference in wheelbase.
i agree with the above. one thing to add, if you know the person who did the changes and you agree he does excellent work then consider buying it. but if you don't know them, then stay away. the third mj looks like cosmetic changes. worth taking a look at. dave