Replying to this comment once more in case anyone else is interested. I believe the museum in reference is Takayama Showa-kan in Gifu prefecture[1].
Originally I found a Showa Museum in Tokyo[2] but the aesthetics of the one in Gifu were much closer to what we had in mind in the context of the Shin-Yokohama Ramen Museum's "alleyways" and the arcade at Super Potato.