Hi JimK,
Your timing is excellent, as one method to accomplish this was just discussed yesterday in a post by Ahab: [url]https://forum.literatureandlatte.com/t/best-way-to-get-edits-back-into-scrivener/44235/6]
One key point in Ahab’s method is copying the revisions into a fresh folder inside your project, so you still have the old version intact if you need to consult it.
Ahab didn’t get into the specifics of how to avoid rogue formatting, I’m on Windows Scrivener, so things may be slightly different for you on Mac v3, but using Paste & Match Style has always worked well for me. Or pasting into a text editor (whatever is the Mac equivalent of Windows Notepad) and then copying into Scrivener will strip out all Pages formatting.
Experiment by copying a few chapters into your project and then running compile to see how it looks. Or perhaps someone with Mac-specific knowledge will reply here. 
Best,
Jim