UPDATE: The seller that has the Chappell and Bosworth catalogs has put up more library music catalogs for sale on eBay. Not only did he put up some more Chappell catalogs, but he also put up at least one catalog from a few other labels, including Paxton, FDH Mood Music and Southern. The Paxton catalog listing is an interesting one, because it also includes a picture of the 1963/64 supplement list, which fills up a few more gaps in the 78 catalog.

Here are the tracklists for the 78s that had gaps before this image was uploaded:
PR.759:
A1 - Royal Charter (Conrad Leonard) (2:11)
B1 - Lazy Lover (Leighton Lucas) (2:58)
PR.762:
A1 - Wistful Waltz (King Palmer) (1:35)
A2 - Cuckorana (Harold Geller) (0:13)
A3 - Indolence (Harold Geller) (0:13)
A4 - Smokey (Austin Rayner) (0:13)
A5 - Sambette (King Palmer) (0:13)
B1 - Top Brass (Cecil Fry (Andrew Fenner/Walter Owen)) (2:00)
B2 - Battle Of Words (Peter Yorke) (1:03)
PR.763:
A1 - Drumming Hooves (Edrich Siebert (Stanley Smith Masters)) (1:12)
A2 - True Blue (Edrich Siebert) (1:43)
B1 - The Big Match (Larry Ashmore) (1:20)
B2 - Spirit Of Daring (Conrad Leonard) (1:35)
PR.764:
A1 - The Lonely Tree (Jack Jordan) (1:32)
A2 - Recreation Time (Peter Yorke) (1:33)
B1 - Spanish Holiday (Rupert Paul (Paul Lewis)) (1:25)
B2 - Highland Holiday (Rupert Paul) (1:08)
PR.767 - Four Moods:
A1 - Romantique (Dolf van der Linden) (1:44)
A2 - Whimsical (Dolf van der Linden) (1:18)
B1 - Dramatic (Dolf van der Linden) (1:15)
B2 - Comedy (Dolf van der Linden) (1:27)