Currently, I'm using a late-2013 iMac with a Core i5 processor, running MacOS 10.12 "Sierra" and looking to clean-install MacOS 10.14 "Mojave" in the near-term. I want to stay at 10.14 "Mojave" on the old iMac for as long as possible. I intend to retain the old iMac to run older Mac software and...