To find photos your best bet is to look through some of the "service station" books. Such as; "The American Gas Station" by Michael Witzel. "Gas Stations: Coast to Coast" also by Mr. Witzel. "A Tour with Texaco" by Rick Pease. "Phillips 66 1945-1954" by M. Kirn. "American Service Stations: 1935-1943 Photo Archive" also by M. Kirn.... Also "Service Stations: Vol 1- American Gas Stations, 1922-1964"
All of these books, plus more that I have... have interior photo shots. Some are more detailed than others because of distance, some shot through the windows and some closer photos.