The only reason Campagnolo didn't put Zeus out of business posthaste was because Spanish patent laws under Franco favored Spanish companies no matter how shameless they were.
But, then you probably know that...I differ with your statement that Zeus stuff was not a clone of Campagnolo. The gear was an obvious attempt to steal Campagnolo's ideas without paying for them, and probably the main reason Zeus didn't have that much presence in the world market in the 60s and 70s..Campagnolo had to be trying to freeze Zeus out wherever they could.
The derailleurs in particular were shameless copies of the Campagnolo originals, right down to the details.
Charles Andrews
SoCal