Quick Google search shows the old HEI in-cap coils as .5 ohm primary. I would think anything from.5 to1 ohm will function/live just fine. I did many GM HEI conversions in the past...ran 12 volts to the cap and called it good. Jeg's HP HEI coil https://www.jegs.com/i/JEGS/555/401...hRcvV4nBJdsSQKplWDtmrkhWkhBoCRDMQAvD_BwE
