What it'll need depends on mileage and how well it's been kept up. Check the fluids, make sure the timing belt has been done or do it yourself. I did mine when I got the truck because I had no record of when it had been done last. Cam and crank seals, tensioner, water pump, and bypass hose should be done at the same time, and I replaced a rad hose while I was in there because I didn't like the look of it. While you're looking at the engine, if the vacuum lines are original/cracking/brittle, might as well replace those before they're a problem. Vac line is cheap. Valve cover gaskets, again, if they're original, they're probably rock hard and leaking. Check for cracks in the tube from the throttle body to the MAF sensor, and if it's torn, check your engine mounts. Check the front wheel bearings, they may need adjustment and/or repacking (you have to take the bearings apart to replace the rotors, so if it needs those, plan for both at once). If it's still got automatic locking hubs on it, consider upgrading to manual hubs. Also check for corrosion issues. These like to rot in the left side floorboard where the gasket for the Y pipe fails and blasts exhaust right at the floor (which can set fire to the carpet), and under the back seat. Mine also had rust in the right rear floor (wasn't expecting that) and the left rear wheel well, in front of the wheel. And of course the frames like to rot in the back, over the axle. And speaking of things that catch fire, check/clean out the heater box. On left hand drive trucks (not sure if you're RHD or LHD in NZ, and I've never been into a RHD dash), you remove the glove box and the plate behind it, remove the blower motor resistor, and then you can clean out the pine needles and leaves that accumulate between the fan and the aircon evaporator. It's not super common but I have heard of hot blower resistors setting that stuff on fire. I glued a screen over the intake to my blower motor to keep the mice out, and it keeps the leaves out too. Check for play in the front suspension joints, including the steering linkage. If the strut rod bushings (rear of the LCAs) are original, plan to replace them--they usually look fine and they're usually trashed.
Oh, and the manual trans needs to be overfilled to keep it happy. Make sure you use the correct fluid.