I am not a native speaker but I listen to Japanese radio from time to time ...
I always hear newscasters say "よん、なな、きゅう” for dates, although I am sure that if you say し、しち、く the Japanese will understand you... :)
1997年 --> せん きゅうひゃく きゅうじゅう なな ねん
1947年ー>せん きゅうひゃく よんじゅう なな ねん