Deejay, if a new clutch-half is out of balance, it would be time to take it back to where you got it, and exchange unpleasant remarks with the supplier. However if that doesn't work (either because they are all out of balance, or because it is the other, output shaft half that is out, not the new engine shaft one), it is traditional to correct the unbalance by putting one or even two extra washers under one of the three bolts that hold the two clutch-halves together.
I suspect that the dummy bolt that replaced the captive cotter in Salty's clutch was put there in order to bring it roughly into balance.
