Without seeing the project there are several questions and possibilities -
1 - Export a Press Ready PDF and instruct your printer to print all in Pantone 280. They would print all as grayscale and run Pantone 280.
2 - Add Pantone 280 to your swatches. Highlight all type and change the color to Pantone 280. Convert all links to gray and color them Pantone 280.
Thanks Daniel! What about a logo? It is a JPEG image...
If the Brand Identity is always expected to be Pantone 280 than the logo should exist as such. Ideally a logo should be designed in the expected color, in grayscale and in black & white. Are the original native files available for such? Always lean towards using a vector image format if available.
It's important to know how this is to be printed. My answer "1 - Export a Press Ready PDF and instruct your printer to print all in Pantone 280. They would print all as grayscale and run Pantone 280" only works in traditional offset. If this is being printed digital answer 2 applies.
For a jpg open the image in Photoshop (or equivalent) and convert it to grayscale (giving it a unique name; save your original).
Back in InDesign select the image with the Direct Selection tool and apply the Pantone Swatch.
Thanks a lot Daniel!