Will to Power and Artifactual Human Eugenics

In the Prologue of Thus Spoke Zarathustra, Nietzsche alludes to the overcoming of Man by the Superman, a process that he later terms Self-Overcoming, which is a mode of the Will to Power. Now, 'man' is ambiguous--it can connote either the species or an individual member, but because of the common association of Nietzsche with Individualism, his Superman in this passage is usually interpreted to be an individual entity.  However, in #960 of the Will to Power collection, as Kaufmann insists, what Nietzsche posits as superior to humans is a "race", to be produced by miscegenation, not by purification, as has been held by Nazis and others.  So, in at least that passage, Artifactual Human Eugenics exemplifies the Will to Power.