Try a test lamp on your coil terminals. The earth clip of the light to the -be of the coil and the test light tip to the +ve, crank the engine as see if the test light pulses. It should pulse as the trigger wheels in the dizzy passes the pick up. There should be a little black resistor inline with the blAck white/ or blue white negative side of your coil, this should be about 670ohms I think. If your plugs are dry then it will be something related to the trigger wheel and wiping I'd Imagine, check the trigger wheel air gap maybe?