The leads should have copper wire cores. There should be no discernible resistance in the leads alone.
The ends which clip onto the spark plugs should be around 1000 - 1100 ohms.
Measuring end to end of any individual lead should not be more than this 1000 - 1100 ohms. (Of course this includes the metal end cap)

There is around 1000 ohms in the distributor cap per outlet and another 1000 odd ohms through the rotor button.

Here's the plug end. On this unit (Beru) there is an actual etching of the resistance.