It appears that someone completed Gibb's work: The Travels of Ibn Battuta / A.D. 1325-1354 … / Volume IV / The translation completed with annotations by C. F.

It appears that someone completed Gibb's work: The Travels of Ibn Battuta / A.D. 1325-1354 … / Volume IV / The translation completed with annotations by C. F. Beckingham / 1994. Found that listed on the Hakluyt Society's website, which published a edition of the Cambridge volumes for their members. It appears they worked to complete the translation in the 90's.