How to install WP 8.0 SDK if WP 8.1 SDK is installed?

I have the Windows Phone 8.1 SDK on my dev pc installed together with VS 2013. I need to open some WP 8.0 projects in VS 2013, but I can't do that without having WP 8.0 SDK installed.I have the Windows Phone 8.1 SDK on my dev pc i