You have an 11 hole water pump. That's typically 1969 and up. It will fit, and you should not have any problems except in the case where you have one of the cars that was built mid-produciton when the switch from 8 to 11 holes was made.
I think replacing the water pump pulley with the corerct one solves the problem. I think Jusride may have dealt with this a while back. The difference - as far as I remember - is about 3/4", or the width of one pulley groove.
