You coulda just asked me dude haha.
Both the 559 and 659 ORC clutch use their "Type A" release bearing that is 67.1mm diameter
http://www.paramo.jp/vp3.php?ci=ogur...echnical_13_en .
It's available to order on Nengun supposedly:
https://www.nengun.com/orc/release-bearing
The nissan part number for the bearing is 30502-14601, they use an oem nissan bearing from a pickup and can order it really anywhere.
As far as the sleeve, it SHOULD work with 16mm or 18mm sleeves, according to ORC documentation:
http://www.ogura-racing.com/pdf/partslist.pdf
OEM part numbers:
16mm: 30501-02C74
18mm: 30501-S0284
(I'm 99% sure one is literally a 350z clutch bearing sleeve, same as the one I used with my OsGiken twin disc)