The previous owner did some strange things on how he laid some things out, but I knew the owner of the HVAC company (who had since passed away) who laid out his 3 HVAC systems decades ago (even before I moved to NC), and I do know they were laid out to the "T" and done correctly with both a manual J and manual D.
You've given me something to worry about, but being the original owner really kind of went out of the way to do things right, so my fingers crossed on the popcorn ceiling.
Interesting, you think that would be a concern when you do a home inspection for selling wouldn't you?