What did you end up doing about a radiator? I am restoring a pretty beat-up MC21 and while the radiator doesn't have any holes it is covered in corrosion. I am wondering if I can get it blasted of if I shouldjust get a replacement. I would like to keep it all OEM but this looked tempting:

http://www.ebay.com/itm/RADIATOR-HONDA-NSR250-MC21-MC28-PGM3-PGM4-/252501853393