My business is stuck on Pages 4.3, which was used to create a complex application. Migrating to current Pages version isn't possible. (I've tried, it just won't work.) I'm running the app currently on macOS 10.14.6 and Pages 4.3 is slow and unstable. So I want to rebuild a fast newer Mac with an older version to get the best Pages 4.3 I can. I know, I know, Pages 4.3 is buggy and weird, but it's what I need. Any advice on which macOS would be best?