Father-Son 1974 Duster Project

Sure sounds like your ignition isn't keeping up. Do you have another coil you can swap in?
The boys over in small block tech are telling me there is is a gap adjustment in the dizzy that could be open more than it should be. They also thing my initial timing is way too high at 20* They recommend I set it at 5* to start because the stock dizzy can give you up to 30* more advance.
I have a new, not remanufactured distributor I am picking up tomorrow.