The Lark Club was an articulated 3 unit car, with the middle car sharing trucks with the other 2. The articulation made it possible to have a it almost completely open between the 2 service cars, so the diner lounge space was 2 cars long. The first car was a dormitory/kitchen, the second was the diner, and the third the lounge, although the "diner" and "lounge" sections did double duty. They served dinner and breakfast, but breakfast was much more popular than dinner, and, of course, the call for lounge seating in the morning was not great. Only 8 tables were pure diner tables and only those were set up to serve dinner seating 24. The rest of the diner had seating somewhat like todays Cross Country Cafe cars, and served as an extension of lounge space. The opposite was true at breakfast, when the entire diner was set up for breakfast, as well as the forward half of the lounge, seating 64 at one sitting. From 1949 to 1957 they even had a phone booth and mobile phone service. Doesn't seem like much today, but it was a very big deal then. They ran on the Lark until 1965, although in the later years, menu selections and service levels were greatly reduced. The Lark itself survived until 1968, and was the last train SP was able to successfully discontinue until the advent of Amtrak (although not for lack of trying).
If you can find the excellent Shine/Ryan book, it has numerous pictures of the Lark Club interior, including builder's photos taken by Pullman when the cars were brand new, as well as shots of various menus and ads.
Unfortunately, neither of the Lark Club cars survived, although a very similiar Cascade Club is preserved by the Pacific Locomotive Association in Niles Canyon near Fremont, CA.
I never had the pleasure of riding the Lark, although I have seen it. Fortunately, I did have the opportunity to ride Santa Fe's superb Super Chief. My first ride on the coast route was in 1958 aboard the Coast Daylight as a child, when it still was in full Daylight regalia. In 1970 I rode the Pacific Railroad Society's "Mountain Outin'" special over Tehachapi Pass. It had a Shasta Daylight triple unit Coffee Shop/Diner in its 22 car consist, which I remember well.