Ximan is right, the original offset was really only for the initial version after the change to UOP. As UO was patched, the files seemed to become more corrupted. The converter "works", but the resulting files were becoming more and more corrupted.
There probably won' be an update to this; I don't want to become zen with the inner workings of those file formats. Ximan has a great working knowledge of the formats now. Hopefully Cheffe can use his input and expertise to make it so this won't be needed going into the future.