Installing old Cubase versions on an external hard disk

Hi everybody,
I’m actually running C11 pro on a Mac Mini late 2012 with OS Mojave and I’ve just upgraded my system hard disk (250 GB ssd to 1 TB ssd) and reinstalled everything from scratch so to have a clean system.
I’ve kept my old hard disk in an external case and I’m asking if, as I need to reinstall C7.5 and maybe older Cubase versions to recover old projects, installing them on the old external hard disk could someway interfere with the new hard disk and the new installation.
Thank you for helping,