Advice for getting Campagnolo Zonda wheelset on a 2000 8 speed shimano rsx
Campagnolo (not Mavic) make a Shimano-compatible cassette body for the Zonda. 

It's the same unit as they also use on the Fulcrum wheels and it will take a genuine Shimano cassette directly.

Whilst the cassette body is advertised as 10/11s, it will work fine with 8s - the spline pattern on the inside of the cassette sprockets is the same.

You will need to use the supplied spacer under the cassette in order to lock it firmly in place.

HTH, Graeme - 
Velotech Cycling Ltd - 
Campagnolo main UK SC