Hi Alex,
Use the Modifier on the ‘body/head’ and set the cutout as it’s Object. Set the Boolean to Difference (the default) and don’t forget to hide the cutout Object (also disable Render for the cutout, before you forget).
There is a great course here on CGCookie: “Modify”: in particular this Lesson might help: https://cgcookiecom/lessons/lesson-3-boolean-modifier
