It'll be fine. 8, 9 and 10sp freehub carriers are the same. Your '9 sp' Ventos will take any cassette of those three.
I don't think so, Campag went through 5 freehub designs in the 90s.
@Skülly started
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It'll be fine. 8, 9 and 10sp freehub carriers are the same. Your '9 sp' Ventos will take any cassette of those three.