The Shinjuku Historical Museum 新宿歴史博物館 has a database of over 500 images of (mostly) postwar, pre-1970s Shinjuku. See their website for photos.
I stumbled upon a series of photos from circa 1952-1955. Here are two version I stitched together. The left side of the photos shows the east exit of Shinjuku Station; beyond the station is the Yamanote Line tracks and, in the far background, mountains.
Here is the first panorama:
Here’s the same panorama, merged using a slightly different method:
One of the first photos in this merged image can be found here, labelled:
These photos were taken from approximately this location: Google maps
Among the landmarks visible in this photos is the old Kinokuniya Bookstore 「紀伊國屋書店」:
- SHINJUKU STATION IN 1957, FROM “DANGER STALKS NEAR”
- Photos from 2017: Shinjuku from the Takashimaya department store rooftop