BCLK tweaking allowed even with multiplier changes and using either DDR3 1333 or DDR3 1600RAM.
DDR3 1600 would just give you extra options to play around with if you eve want to move beyond playing with just the multiplier.
Either one will be fine. If you choose DDR3 1600 your motherboard could choose to run it at DDR3 1333.
You can just set the memory to AUTO and let your motherboard do the hard stuff figuring which setting it wants to use.