I generally used the 1,000 ohms per foot rule of thumb.
RFI (radio frequency interference) suppression wires would be more, 3,000 to 12,000 ohms/foot, while "race" wires could be less, 500 ohms/foot.
Infinite resistance means a bad wire, obviously, but my best test is to pull the wire off the spark plug with the engine running and see if you have a good, bright spark 1/2" to 3/4" away from the plug. This also tests the coil output.
HTH.
