Oh, I forgot saying what my problem actually is . The game crashes when I open the blocks inventory (it worked before, just didn't do the GUI animations yet). I'm having an error in the Tile Entity code (or so at says) at the "if (this.tileIsolatedFurnace.isBurning())" line.
It's still a nice idea to also change the way it shifts faces, I didn't like that part either, didn't play around with the changing faces.