Hi,
I have a 2.2i in my GT and it even has a hot cam ( it is tuned)
I have always used my original radiator. I do not use the car very often, but there were never problems with this car running hot.
You can consider an electrical fan. Till now I didnt need it and the only reason i would consider it is the fact that an electrical fan only runs when needed.....
For sure it depends on the climate.
The 2.2 has a lot more torque so a bigger clutch is no luxe item.
Ones, when driving and spinning a bit wild and crazy, I wrecked the original clutch, infact the pressure plate .
It came out of balance and it cut my Getrag 5 speed housing almost in half, so the havy vibrations wrecked my startermotor to and so on........
Now i have a 240mm clutch and pressureplate from an Opel rekord 2.2i
I also did install the getrag 240 5 speed.
In my opinion this is not a must but a nice thing to have, because the 2.2i has lots of torque so it is nice to drive it at low RPM's.
The 4th gear ratio on the getrag is 1:1 so the same as the 4th gear of the original gearbox, but you have the fift gear (ratio 0.804) as some sort of overdrive ,ideal for easy cruising.
You should consider installing bigger brakes.
In front ,I mounted the original (double) ventilated discs 246mm and the calipers from an opel rekord 2.2i.
In the back i didnt change anything.
I did install the master cilinder of the opel rekord 2.2i
greets
Geert