I have MIIIF which is quite similar- my sample can do bclk 265- so far tested only one chip- my new 661 and 670 should be here next week 

 hope for nice pts boost in wp category for dual cores 
 
about cbb and cb there is simple mod:
 
I didn't test mine before mod 

 but after mod I din't have cbb- only cb @ ~150C, but I have tested only one chip