I wasn't a macintosh user back in the day but for the file archives I frequented (apple II), sometimes files were in BINSCII which was a similar text encoding. The advantage being that they could be emailed inline, posted to usenet, didn't require an 8-bit connection (important back in the 80s), and could be transferred by screen scraping if there wasn't a better alternative.
So this is really random, but Kermit actually could route around your 7-bit issues. Everyone remembers it as a godawful protocol choice, because terminal programs usually implemented the most basic version of the protocol, but if configured correctly it was on par with or better than Zmodem.
Kermit was still useful into the 90s. I had a brief gig helping a friends dad set up an ecom store. Their payment processor got nightly batches of authorizations and captures by model. We were having issues getting our machine to talk with their machine, and surprisingly enough I was able to get an actual engineer on the phone. We used kermit to debug the modem handshake interactively while we conversed, figuring out the magic Hayes incantation to get them happy.
