They also have a sheave replacement pack:
http://rigrite.com/Spars/Kenyon_Spars/4060-MORC.html part K-10658SK. It is $199. It has the sheaves and bushings you need, but if you drill out the old sheaves, you'll also have to replace the clevis pins (7 total). Not sure how long they have to be. If anybody knows, I'd like to know too.
