Won’t start No Spark.

Last year was heading to a car show and my 440 quit running. We established by the side of the road that there was No Spark. The car is a b body with a 440+6. At that time it was using an aftermarket magnetic pickup distributor and an MSD CDI box. I first replaced the pickup with No Results. Then a new MSD (Street Fire) box and a Pro Form factory look distributor and the car started and ran for several days. A new no start condition arrived again same issue No spark. After reading a bunch of bad reviews on that particular distributor I chose to return it and purchased a Summit branded billet one. Car started and ran all the rest of last season. Today I wanted to get the car from the garage and again No spark. I have no spark from the coil when cranking the engine. If I un plug the trigger wires from the distributor and jump them. I can make the coil fire. But not always about 5 out of 10 manually.Wiring looks ok. Do you think I could have yet another bad distributor? Possibly a bad coil ( MSD high vibration) or ignition switch? Running out of ideas. Thanks to all in advance