Mike,
I doubt that the EFI coil will work with a carb ignition. They both have different OHM requirments..
You cant use a carb coil with the EFI so I doubt that you could go the other way.
Carb coils are not very expensive, especially if you consider what it is going to cost to do your project.
I got to say that I have to agree with you on the conversion.. I am thinking the same myself.
I know that the EFI have some good sides but life sure is a lot simpler with a carb and if a carb had been an option on mine when I bought it I would have gotten carb.