I think maybe the shot of Dean with his Porsche (and what I've read was his own recently purchased white '55 Country Squire) was indeed taken at the Casa de Petrol, or a predecessor station on its site. According to classified ads in 1955 issues of
The Valley News, La More Real Estate was at 14325 Ventura Blvd. (The site that shows the ads,
http://newspaperarchive.com, wants at least $10 to allow a screenshot, so you'll have to take my word for it or check out one of the issues containing the small ads, such as that of March 3, 1955.) 14325 Ventura is currently the address of A Touch of Romance flower shop, which is in the Casa de Petrol building or on its site. The real estate office must have been in the space between the casas Petrol and Cascade and removed sometime between Dean's fill-up and the Casa de Petrol shots we've seen here that have '59 model cars in them and appear to have no building between filling station and car wash. Btw the first name appears to me to be "Rosalie" rather than "Rochelle."