nine speed cassette will not fit in an eight speed locating tags are differant.
the way I did mine and it works fine was as follows:-
bought a new record 8 speed cassette from ribble
buy one sprocket and adapter from Marchisio, sold by various mail order outlets.
buy campag 10 speed spacers, you need 6.
you then need to get the final sprocket machined down to the same thickness as the new 10 speed spacers.
I have converted a set of Mavic Heliums and also a chorus 8 speed
and work perfectly with 9 speed ergo levers.
I have a mavic M9 cassette that came with individual sprockets and spacers for campag.
This may well do it for you.
Have a look as I am not using it and would be happy to sell on.
J.