And the insides on the right. The 1975 binder (top images again) has the Central (left) and Pacific (right) Best Nine. The Central had only nine players, one per position. But the Pacific League has 11 - they usually have a DH (starting in 1975) and there must have been a tie in 1974 ... (checking) ... nothing shows. And I'm too lazy to figure this out right now. I'm sure NPB Card Guy will chime in if he knows anything!
And there's another photo of Nagashima here. He had just retired at the end of 1974, but managed the Giants from 1975-1980. He brought the Giants to their worst record ever in 1975, though, and only last place finish, with a .388 winning percentage. He did give them two Japan Series appearances in those six years, though they didn't win either time.
It's not terribly hard to find album prizes from the early 1970s, and if you're willing to get a less-than-perfect example they aren't too expensive - a few bucks, usually. The 1980s are another story.