Does the keyway slot have any correlation to the actual engine timing?  I would believe that mass production of these crankshafts were done in such a way that they would be compatible to the damper pulley assembly, pretty much as a matched set.  If not and they were manufactured helter skelter where ever the milling machine decided to cut the slot then you would have a hard time installing a pulley and finding TDC.  Reason I ask is I was told when rebuilding the harmonic balancer, the balance ring is vulcanized into the correct position in the pulley assembly.  BUT my balance ring has no marks on it, the small "V" is only on the edge of the first pulley. I believe in correct factory timing settings to make it run decent.