[AZKen]

The next step is to remove a sparkplug. Attach it's wire to it. Touch the threads on a good clean metal ground spot on the motor and crank motor to observe spark. Hard to see in daylight, so watch carefully.
The backfire was probably your pumping gas, unburnt gas, into the system. It can also be something worse. Do the plug test and be sure of your result, very important.
I assume the negative on coil has a black wire to the distributor??????????? and that wire is not frayed and touching distributor housing.
I agree, probably time for new points and condenser of there is weak or no spark at plugs.
Explain specifically how you tested to get "no spark out of the coil".