I believe you have to replace them as a pair anyhow. They are bored and machined as a pair to guarantee alignment. Might be easier to just get another old crankcase.
well, I have a 066 that is cracked behind the clutch. Not all the way into the crankcase, but the shock mount behind the clutch is broken off. Sounds like I'm out of luck unless I buy a whole new crankcase. They quoted me 320 for the part.