This menu doesn’t say whether it is for lunch or dinner, but it probably served for both. In 1956, the morning Internationals left Seattle and Vancouver at about 8 am, arriving at the the opposite terminus around noon. Then they returned, arriving around 5 pm. They then returned again, arriving around 10 pm. The second run could serve a late lunch while the third run could serve a late dinner.
The menu offers “plate meal number one” with a choice of entrées, juice or soup, potatoes, salad, vegetable, bread, dessert, and beverage. The entrées were fish for $2.25 (about $15 today); prime rib for $3 (about $20); or “chef’s suggestion” for $2.50 (about $17). Plate meal number one has a choice of four entrées, all for $1.85 (about $12.50): fish, chicken with noodles, cheese omelet, and minute steak, together with potatoes, vegetable, bread, dessert, and beverage.
The a la carte side has seven sandwiches, three salads, and several desserts, breads, and beverages. Unfortunately, this menu is not in my collection, but an ebay dealer had posted some reasonably good scans of it that I stitched together into a PDF.