Finally found somebody with more into a 16613 than me! Noice! I've owned three WM9's and they have the high crown position so the gen 3135 movement goes right in. As I recall the bracelet looked like it was 14k, and not 18k like the MBW bracelet. Nothing's cooler than a gen 3135 movement. That's the ultimate upgrade. Sweet watch, nicest one besides mine I've seen. 
Here's a comparison shot of my WM9 and the MBW. (MBW on the left) You can see the difference in color of the bracelet.
Here's a comparison shot of my WM9 and the MBW. (MBW on the left) You can see the difference in color of the bracelet.