I want pre-1980 state level VEP turnout rates

I have looked into computing pre-1980 state level VEP turnout rates, but the data are elusive. The Census Bureau only computed citizen voting-age population (CVAP) in 1970, when the voting age was 21 in most states. The Census Bureau did not ask a citizenship question on the 1960 census, although it did so on the 1950 census. The Department of Justice only began reporting complete correctional population statistics in 1978. I continue to look for the necessary data to compute accurate pre-1980 VEP turnout rates, but for now I have decided not to release incomplete data.