IIRC, when you use the HEI module, you do NOT want a resistor in series with the coil. I was thinking about doing this conversion. I emailed the guy as gofastforless.com and he told me that the current limiting is build into the HEI module, and he said to run 12V straight to the coil and let the HEI module regulate the current.

I have not actually done the conversion yet, so I cannot say how it works with straight 12V.