Toyota LJ78 are the 5 door (suv) version of the Troop carrier (75). These are one of the toughnest trucks you can buy and are more than capable for what you want. Here in oz they are everywhere and are used for just about everything. Often used by converted to campers by hire company's. They do a nice little conversion, check out (britz Australia) for inspiration.
I'm not sure about the engine size you quoted, I thought they where all 6 cylinder 4.2 diesel & 4ltr Petrol. I would have to check your exact model out. Like I said not sure.
If it is one of these engines thou, they are great and will easy do 400000kms. They can overheat a bit, so bigger rad or better fans. Also the gearbox can get a bit crunchy with bad driving and abuse. Other than that you can't kill em.
For an overland trip they are great,plenty of room, reliable and not too bad on fuel. Not as good as say a Nissan patrol of road. More than adequate for the most stuff thou. With some tyres on we would be just splitting hairs between the 2 of them.
Have a good trip
""Why cant we all just get along?"" - - No forget that ! why can't you all just get out of my way ?...