As Aletys notes on the Ultima 6 Project forum at the Project Britannia website, updated maps are available, in both French and English, for the Ultima 6 Project:

PDF Map Books were updated to correct some errors (dungeon & Gargoyle lands file dates on these are 2/19/2013):

• Britannian dungeons had the wrong map for Hythloth level 4
• The Gargoyle shrine maps were rotated incorrectly

Additionally, the maps themselves are of much higher quality than before. And you can grab them now, from the project entry!