Wiring Question?

hi guys IM new to this site but i like what i see i have a 74 duster with a pretty respectable 318 that iv bin having wiring problems with some days it starts right up other days nothing it cranks but no spark IM not much on wiring but i have checked for bad connections it has a new voltage reg. new ballast resister accel super coil with a coil ballast resister chrome ignition box at one time I was having problems with the ignition switch and mine is the model where the switch is buried inside the steering column so I took the short cut and put in a starter button this car has always had a miss in it and I always contribute that to a big cam or carb adjustment but I wondering if its an ignition miss anyway if any body has any ideas where to look the car has nothing right now.
battery is fully charged no spark ballast resisters have contanewaty it will crank if i jump the starter relay but it wont start
help please
ray