Okay, so… uh, this is a big swath of area to update! If my math is right, we're talking ~182,556 blocks based on the corners you described above. The mod can handle that fine, but I'm not sure the server is going to be happy about updating ~713 chunks (each is 16x16) all at once. Perhaps I'll go about slicing this up a little bit at a time.
And just to be sure, does this roughly cover the area that you're talking about, Ken?