Even new Beru cables will tend to short out quite easily due to a very poor design, no resistance in the wire and lots of resistance at the plug ends which tends to make it very favorable for the spark to short out at the wire wherever a path of least resistance presents itself, like your hand.
You might try some other options as presented here:
which spark plug wires??
Cheers,
Joe Garcia
Rewood PCA since 1976 (former tech chair)
86 Carrera