i'd either go with a 22r(i own a toyota, know quite a bit about them) or i see that many isuzu trucks had a 2.3l carbed engine, that'd probably work
the 22r and toyota transmissions that went into 4x4 trucks would probably be a good bet. the transfer case output is on the passenger side, not sure about the luv(as i don't own one...yet :p), but i think it's the same as the luv. if you take this route, try to get a W(like a W56) series transmission instead of the older G series such as a weak G52 or G53 that often blew up after 200k because the bearings were too small.
22r engines are well known for their reliability, they usually go 300-400k miles until a rebuild. also, parts are everywhere and they tend to be cheap because the engine was made from 1981 until 1995 at least. it's available in a carbed version, a EFI version(22re), and a rare turbo version(22r-te). stock, the engine isn't blazingly powerful, with about 95 hp, but you can get a few dozen ponies by adding a weber 32/36 or 38, as this motor was notoriously undercarbed. a header can spice things up a bit too, although often to the cost of some torque. but i'm sure that if a properly equipped 22r in a toyota 4x4 can turn 35" tires without any problems, it'd work great in a luv
i tow my 13' boat around with my toyota 2wd, bone stock, the only place where it gets scary is on the freeway, since the stock carb bogs it down a bit