yes you should be able to run it with out a ballast resistor http://www.msdignition.com/Products...ent/8202_-_Blaster_2_Coil_Hi-Performance.aspx
You already have a resistor wire from the swich feeding the coil. Also the Dura Spark II didn't come out until 1976. Are you sure you don't have the small cap Dura Spark I?