Complex sentence: Assembleymen were elected by all eligible voters of within a district, while Councillors (before 1963) were only elected by landowners within a district, but were elected since in the same manner as Assemblymen.
Split into simpler sentences: Assembleymen were elected by all eligible voters of within a district. Before 1963, Councillors were only elected by landowners within a district, but afterward were elected in the same manner as Assemblymen.