check your plug wires to make sure no crossed wires and correct order on cap and fire order 18436572

3 & 5 are ez crossed and do the same crap.

some times a bad condenser will act that way but you wired in elect. this points me to cap rotor wires plugs.

huck fin someone to run their hand down each plug wire while running.

check BR on fire wall to make sure it is good.

check coil to make sure it is still good.

how many volts at the + side of coil in run mode? how much when cranking

been swapping to a points dist for yrs myself and only have had a bad condenser/burnt contacts/cracked cap/crossed wire act like you describe.

you have ruled out the point dist system so cap/wires/plugs

while cap is off roll engine and check your timing marks and rotor to see where they line up. check wire order on cap against rotor

rock crank back and forth to see how much it takes to move rotor 'slack in the chain'