Every Floyd Rose Special I have seen have had different proportions than an OFR. I wouldn't expect any parts to be interchangable. Even the locking nuts aren't, so I'm positive that this has to be so by design.
I own two FRS guitars and the parts are interchangeable with my two OFR guitars.
The FRS stay in tune perfectly like the OFR, the only difference is the block needs to be replaced, and the saddles are inferior quality.