Hi Mark
Thanks for posting.
Muli is probably the closest Google Font available to Century Gothic. Using Muli or another close alternative would be the easiest way to proceed.
Century Gothic is a premium font as far as I’m aware so you’d need to purchase a web license or use a service like Typekit: https://typekit.com/fonts/century-gothic. Implementing a font from Typekit would require light custom development but most of the code is provided by Adobe and other similar services.