Lots of parts are interchangable
2J's have TA21 carbs 5Ks have TA22 carbs
If the bike has a PGMII it's likely a 5K
There are lots of subtle differences. Best get a parts book and check out the pictures
This is the list I complied a few weeks ago
Moriwaki Man (NSR World)
David Silver (UK)
Lings (UK)
Yahoo! (Japan)
eBay
General google
Various breakers
I Love Motor (Japan)
CMS (Holland)
DK Motorcycles (UK)
_________________
Why do things simply when you can complicate them