I wasn't sure if I would have luck picking up vintage baseball cards at Nakano Broadway. I hadn't seen anything promising the first time I visited, but since many of the shops were closed I kept my hopes up. And I was successful this time around. There were two locations that had vintage cards. One was one of the Animate! stores carrying a selection of Calbees.
(Thanks to NPB Card Guy and Jason for help in identifying some of the cards above.)