If I'm not mistaken the Magnum 8 has a points free magneto type "electronic" ignition. I'm pretty sure this was the designation they gave it when it replaced the points ignition K181. As far as a battery powered capacitor discharge type ignition for them, I've never seen one myself but I think there are some out there that the puller guys use for the K singles, but I think the system is timed by the points on the K's, so they wouldn't work on a Magnum.
-Fordlords-