I actually rebuilt my site in squarespace last week and called Google to talk about this again. They had specific instructions for squarespace code injection for Google. If you go to Settings, Advanced, then "Code Injection." They recommend putting in the header from there. Footer works but for whatever reason they now have more specific information in partnership with squarespace for this. I'm not sure what their take is on conversion being email, or if they are tracking all activity on the site with that code.