Larry & McGrath:
At the time of the Communist Manifesto, that is in 1848, Marx's interest in democracy was tactical. If everyone could vote, then theoretically the dictatorship of the proletariat could be brought about quite simply. But Marx did not ever, at any time, talk about the specific form a dictatorship of the proletariat would take. He was a Left-Hegelian, which means what ultimately concerned him was not a change in forms of government, but the realization of the potential of mankind. That is, when the proletariat triumphs, history will be over, heaven will exist on earth, and such trivial concerns as forms of government will just be irrelevant. That is why, despite his many fascinating insights, Marxism is an ideology, not a science. It is closely akin to Christian millenialism. And greatly as I respect the old guy's trenchant mind, it is impossible for me to believe in Marxism.
Needless to say, Marx's thought did not provide Lenin with any guidance about what kind of a system to build in Russia. That's precisely why Marxism appealed to Lenin and others like him. No annoying rules that tie your hands.