What is the car doing, that is not right?
What is the Battery voltage, sitting, at idle, reved up?
What is the Dist Batt +, ign on, at idle, reved up?
Black plugs could be fouled, and misfire even after changing Carb, and Dist.
Broke valve spring, Cam going bad, or even Vacuum, or Egr leaking. Will a Vacuum Gauge read correct, at idle, and down track?
Does a Timing Light flash, show a misfire? If so, which ign wire?
Is the fuel pressure correct, at idle, and down track?
Does a Comp test show good on all cylinders?
With a Reluctor pickup, if it drops just one cylinder, it can cause the others to misfire!