Welcome to the club.
Its a great swap!
The 1KZ-T is the engine they should have come with from the start.
The amount of torque and power compared to the gutless L series engines is mind blowing, its awesome!
If you can find a 1KZ-T which is the manual fuel pump version the conversion will be a lot easier as you only need one ignition live to the fuel pump to make it run.
If you fit the much more common 1KZ-TE you will have to deal with a lot of wires, sensors and an ECU.
You could however fit a manual fuel pump to a 1KZ-TE.
But as I'm guessing yours already has an ECU its possible you may be able to connect your loom straight up to the new fuel pump, maybe.
You will need a suitable bell housing to mate your R151 gearbox to the new engine.
The exhaust will need to be modified/replaced to suit the new engine.
The airbox will need changing to a bigger one, the KZJ70/KZJ78 uses an 80 series filter so you could probably use an 80 series airbox although you may have to modify it slightly.
You will need to modify/replace your engine mounts as the 1KZ engine mounts 20-30mm further back than the L engines. The first time I did the conversion I extended the standard chassis engine mounts back. It wasnt pretty but it worked and lasted years. The second time I made some adapter plates to go between the standard LJ chassis mounts and 1KZ engine mounts. This worked well and meant I didnt need to modify the chassis.
Most of the other bits will be reasonably straight forward, such as connecting the radiator, throttle cable, etc.
Hope that helps.
