I'm not presupposing anything. In particular, I explicitly mentioned that the zombies will have an eternity to learn the lessons of peace. You say "since [the transformation] is likely to be a slow process" but have provided no actual arguments or examples as to why that would cause a problem.
We already know what happens when a tyrant uses edo tensai. He raises an army to do his dirty work. But we're not talking about a tyrant. We're talking about the Hokage.
Also, how is the potential for coercion through mind control worse than the mind control the Moon's Eye Plan depends on?
Presumably the fact that they are in charge, and would therefore have nothing to gain.Also, I think its a pretty bad idea to let the Kages have complete control everyone. In a society of immortals, we have given a few select individuals with the power to control and pass judgement on everyone else (by erasing their personalities). What's to stop the one of the kages from exploiting this ability down the road.