in the itch.io app you can use the "Manage" button to switch to another version, so you can install 1.6.4 there, or 1.7 later, and switch back and forth. Just note that savegames are not compatible.
Much older builds (up to 1.5.1) still exist in the Google Code Archive (https://code.google.com/archive/p/lambdarogue/downloads) although I requested Google to delete that page, to avoid confusion.
The last MacOS LambdaRogue build from 2013 is available here: https://sourceforge.net/projects/mac-lambdarogue/ Please note I can't support MacOS anymore, because I don't have access to a Mac anymore. My main focus is on Linux and (secondary) Windows.
However, I think anything before 1.6.4 is much worse than what we now have, esp. with 1.7. :)