Good to get your message. Upvote for sure.

There were a lot of "non-standard" elements to work around through time, since there wasn't actually a real standard. More info can always help from many viewpoints and experiences and still not cover it all, young or old the more that have something to give as well as something to learn is a winning combination :)

The CHS values are still present in the partition table along with LBA equivalent, SCSI or not. Only with MBR layout though, not GPT. Some systems have never paid attention to CHS, some have never stopped. Like different forms of DOS.

Which is why a proper USB adapter is intended to just work with a PIO-0 HDD, and usually does unless the data layout on the old drive is so uncommon to be the kind of edge case that would be a show-stopper when connected to a vintage ATA motherboard too. That would require the unique CHS to be manually set in the BIOS to conform to a "custom" layout that was so non-mainstream for some reason when the old HDD was set up.

Then you had "drive overlays" which can get even more challenging when you're connecting old HDDs to newer PCs so often it makes you blue in the face :)