I have a late 2013 MacBook Pro, currently running OS 10.9.5, with a 2 T external hard drive that I use for Time machine backups. I'm looking at upgrading to High Sierra, but want to continue using Finale 2008, for which 10.9.5 is the latest OS that will work. Can I install 10.9.5 and Finale 2008 on the external HD and use my laptop to run them? If so, what is the best way to do that? Can I migrate my current OS, or should I make a bootable clone? Or is there yet a better way?