The only difference from the older ZX-6R's and the B1 models is the overall length of the oil filter unit itself. A direct side-by-side comparison shows absolutely NO difference other than length, the thread, internals and diameter are all the same. So don't sweat it, I've used two insofar with no problems whatsoever.
Just one of the many reasons the Kawasaki is so light this year, they're starting to cut corners I don't like to see. EG - The heat exchanger on the oil filter has a tab to insure that you line it up correctly, well that tab is so flimsy compared to the older model. It was a giant pain in the arse getting that thing on correctly without misaligning it! Not to mention the fact that some sort of LOCKTITE was used to secure said heat exchanger inside the oil galley for this very reason!!!
Chaos, panic, disorder......
my work here is done