Radio noise suppression isnt quite as esay as some might think. I havent perused the auto parts catalogues of late, but if you can find a capacitor for distributor ARMATURE mounting, use it. Its capacitance will probably be about .25-.5 Microfarads (MFD.). ALso, its often wise to install a .1 Mfd./600Volt capacitor in the top of the ignition coil, from the terminal to the shell of the coil, under the cap.
Youll definitely need the generator capacitor, and either a distributor suppressor or a resistor wire from the distributor to the coil. The resistance of that suppressor or wire should be about 15,000 Ohms.
Beyond that, the task becomes a bit more involved. You may need a flexible ground strap from the engine block to the firewall; grounding strap from the firewall to the hood; capacitor from the ignition switch accessory terminal to ground, or other tricks.
You may only need the generator capacitor and the one in the coil. Youll know when the radio is on, to a weak station, or off station.
