Your gtv is a cf2 and the engine you have bought is a cf3. There are a number of differences, notably;
a) The knock sensors. The cf2 uses 3 wire knock sensors where the cf3 uses 2 wire. Obviously the plugs are different... You can only realistically access the sensor nearest the flywheel with the engine out of the car. So swap them over when you have the engine out - they're under the pipe between the stat and the water pump. They also have a torque setting iirc.
b) The crank sensor is different but easily swapped.
c) The wiring harness is different, obviously. Use the cf2 engine loom.
d) The injectors and fuel rails are different. For the sake of simplicity I would suggest you use the cf2 injectors and fuel rails. You can make the cf3 versions work though.
e) As you have already identified, the oil breathers, cam covers and plenum are different. You can lob the cf2 gubbins on to the 3.0 engine but I would make some mods and use the cf3 set up as it allows you to ditch the oil breather gubbins on the back of the cf2 manifold making the engine much easier to work on in the long term.
f) the lower half of the thermostat body is different. Cf3s use one temp sender where the cf2's have two.
g) exhaust manifolds are obviously different.
Posting from memory, probably forgotten something.