We don't have onscreen precedent for the Borg assimilating a lifeless corpse. I guess it would be quite doable, but the mind would probably be gone and not retrievable - unlike in those cases where a person is assimilated alive, then killed, and then reanimated (like in "Unity"), and the mind can perhaps be downloaded from the Collective.
The Borg claim they want to improve the quality of life of their humanoid victims. I guess one could say that reanimating a corpse would be an improvement - but the "client" would be gone. All the Borg would gain would be another walking body, and we don't know if they do that sort of thing.
Timo Saloniemi