As you suggested, I got a copy from PG. It turns out that the chapter numbering of the converted .lrf file was wrong. Chapter 23 was unnumbered and the conversion tossed the title "Chapter XXIII" to the end of that chapter. I probably would have caught it sooner except the last chapter was a bit inclusive and it seemed there could have been a follow-up.
Probably you are right in that conversion of .txt files is the better option even though the .lrf files I've converted have seemed to come out formatted correctly. Probably not as nifty as the .prc versions from HarryT, RWood, et al, but certainly readable. The major thing is I probably would never have found (let alone bothered to download) THe Return w/out encountering it on MobileRead.
Yes, I did enjoy my first dip into sciFiction. Well, I guess Dune is ScFI and I really liked that but it was more years ago than I care to count.
Anyway, I appreciate your extra effort and apologize for the unnecessary inconvenience.