if **** not up to date with the specs they can be found in these links
http://nsr-world.com/specs/html/nsr250/index.htm
http://www.dreamgate.ne.jp/nsr/general/quickref.html
http://tyga-performance.com/site/index.php?cPath=369_378
if you can wait, hold out for an SE / SP 21 their cheaper to modify than the 28s as you dont require the 030 card, and imo look better with the banana swingarm ( i used to have a 28 )
and you get the good bits of the adjustable suspension, i remember reading a thread where someone updated to rvf400 usds, but didnt like them and reverted back to the SE/SP forks after getting them rebuilt
the magteks on the SP and the dry clutch on the SE/SP, why would you want to go wet again...
im getting my bike hopefully soon, i found a 21sp in rothmans colours in melbourne getting it delivered this week
theres 1 on ebay, i think its just an R model in melbourne it does have a fresh rebuild, cant remember if it was just a top end though
happy hunting!