I don't want to sound too dumb here, but I am a newbie. I ordered all the peripheral's as part of the radiator replacement on my 17 Touring - outlet's and inlets because they were corroded pretty bad, and hoses. But on the Lang's site, they refer to the water pump. I am not sure I have one...er, do I?
If you have a new radiator or a good one, you don't need a water pump. Just an inlet and an outlet. The inlet goes on the side of the block under the engine number.
The water pump is an after accessory and the length of the fan belt is different if you have a water pump because the belt drives both the fan and the pump.
I would try the car without the water pump and if it overheats, you can always add a pump later. It is a lot less trouble without one and it will heat up to the normal temperature which is just below boiling. If you put on a pump, you might find that the engine never warms up, especially in cold weather.