I downloaded 2.4.23 from kernel.org (mirror) and my 200GB drive is
detected as such on the (old) integrated CY82C693 interface. This was my
ultimate goal. (I compiled in 20269 support too, and though I haven't
tested it, someone confirmed it works with 2.4.23.) Evidently LBA48 did
not appear until >2.4.18. Go figure.
I would like to thank Mans and (from my post a long time ago) Mathieu
Chouquet-Stringer for offering a correct interpretation. (Note that there
were others in the thread who were not.)