i would suggest a SAS, since making a TTB setup to work properly on your frame will invove a lot of work.
if u dont plan to go on big tires and hardcore stuff(its a 4 banger, so it wont go into hardcore stuff imo) a D30 would be a good choice, u can mount it using the stock jeep susp parts as an example to build yours or mod those to fit. (coil spring cherokee or wrangler)
u would need to make an adapter plate to adapt a Ranger/B series transmission out of a v6, or find a 4 cyl 4wd tranny.
i dont know if you can swap the tail of the tranny housing to a 4wd one.
a divorced t case setup sounds good too. with proper building skills i think someone could make the cherokee t case to work as a divorced unit on your truck.
remember to get both axles to run with a matching gear ratio or thing will go bad really fast.
some people do like challenges and to build his truck, not just to go and buy it imo. maybe he doesnt wants/needs a v6.