You guys are mixing up Zn vs. ZDDP, in at least 3 posts.
About 10% of the molecular weight of ZDDP is zinc, by weight.
So an oil that has 1000ppm Zn, or 0.1% Zn, by weight, is about 1% ZDDP, by weight. The precise ratio depends on the size of the alkyl side chains.
I have a reference that excessive levels of Zn/P/ZDDP can cause tappet or camshaft excessive wear. The excess wear seems to start at 1500-2000ppm Zn or P, roughly, from what i've read.
I also have an SAE article "How Much ZDDP is Enough?"
For broken-in engines without excessive valve spring pressure, the consensus of the article is that 500-800ppm P is enough.
It may be off by a factor of 10 since the figures would imply the ZDDP concentration is greater than 1 million ppm!!!
Charlie