A small Go program that expands older 6144x4096 tile map0.mul and staidx0.mul files into the new sized 7168x4096 files. The right side of the map is filled with dungeon black tiles (land tile 580) at altitude 0. When copying over the new map0.mul and staidx0.mul files do not forget to also copy over statics0.mul!
A windows binary is included in the Zip file but I'm not sure what systems it will support. I would highly encourage any user to compile from the included source code.
I used this to import the UO:R-era map into a newer client. I actually took the source map from the Samurai Empire install disk.