Ah, I *almost* spoke too soon, the mod works, but if I load my previous Magic World 2 save, it says there is one ID mismatch - ID 9100 is mismatched between save and game.
2014-04-09 19:29:30 [SEVERE] [fml.ItemTracker] FML has detected item discrepancies
2014-04-09 19:29:30 [SEVERE]...