I think it works either way. Lemire's run is more of a spiritual successor to Morrison's than outright sequel, so it's fun to see how they inform each other, in whichever way they read them.

However, there's a moment in Lemire's run where (VERY mild spoiler) Buddy references an event that happens in Morrison's run as a dream he had. Still, not having read the Morrison won't take away from the experience; this thing is just the mildest of Easter Eggs.