Here are a couple thoughts to consider on the two main variations of the lwb 70 series.
The manual transmission HZJ77 and KZJ78 are pretty rare and expensive. My understanding is, there is a lot of competition for them at the auctions in Japan. I very rarely see them come up for sale in western Canada. Due to the rarity, both HZJ77 and KZJ78 with manual transmission carry more value than a BJ74.
HZJ77: heavy duty 1hz engine, leaf springs in all four corners, heavy duty rear axle, heavy duty (H55?) transmission, longer front end with round head lights. Has the option of factory electric lockers front and rear. Option for factory electric winch.
KZJ78: light duty 1kz-te engine, coil springs in all four corners, light duty 8" rear axle, light duty R151F transmission, short front end with square head lights. Has the option for only a rear electric locker. Option for factory electric winch.
As I see it, the KZJ78 will be more comfortable than the HZJ77 because of the coil ride. The 1HZ is a pretty tough motor, where as the 1KZ has been known to crack heads if overheated. The 1HZ is pretty slow unless turboed, (very expensive). The 1KZ with an intercooler and more boost/fuel (affordable), can be a very peppy little engine. Although the R151F and 8" diff on the KZJ78 are smaller than the H55 and 9.5" diff of the HZJ77, they are still strong and reliable units. Realistically, I don't think they really play into the equation much. Both the HZJ77 and KZJ78 share the same transfer case. Pretty much everything else is identical except what I've noted above.
If you have lots of money, get the HZJ77 and turbo it. Will be a tough rig, and good for towing up to 2 tons. If you don't want to spend as much, get the KZJ78, install an intercooler, and tow only lighter loads with it, probably only up to 1-1.5 tons.
You could also look for a PZJ77. It is basically the same as an HZJ77, but has one less cylinder, and has the lighter duty R151F transmission.
