Table:
text: Tobu 8000 series
History
1963-1981
Fiscal_year _2_car_sets _4_car_sets _6_car_sets _8_car_sets Total_vehicles
1963 0 15 0 0 60
1964 8 15 0 0 76
1965 21 21 0 0 126
1966 27 27 0 0 162
1967 39 36 0 0 222
1968 47 43 0 0 266
1969 58 51 0 0 320
1970 62 55 0 0 344
1971 62 42 13 0 370
1972 62 41 17 0 390
1973 63 41 22 0 422
1974 68 41 25 0 450
1976 70 41 31 0 490
1977 70 41 31 5 530
1978 70 42 31 9 566
1979 70 42 31 14 606

Question: What is the largest FY1968 6-car set in the history of the Tobu 8000 series from 1963 to 1981?

Question: What is the lowest fiscal year if the total number of vehicles for Tobu 8000 series history from 1963 to 1981 is 490?