Going to an experimental airworthiness certificate would really reduce your aircrafts utility. The FAA has several definite purposes that it will issue an experimental airworthiness cert for. These are on
http://www1.faa.gov/certification/aircraft/ The most popular one is experimental amateur built. It provides the most utility ( once the phase I restrictions are flown off ). However, 51% of the work has to be amateur done. I don't think this would work for your case. The other purposes are research and development and Showing compliance with regulations. From what I understand, the FAA wants a definite flight program/plan prepared and adhered to, thus restricting the utility of the aircraft.
Again, I wonder what would it take to get a field approval for the Lightspeed plasma III. What is wrong with using an electronic ignition system for one mag? The redundancy is still there. Of course there is the Unison Lasar system, but it is not available for Continental engines. But electronic ignition on certified aircraft is not unprecedented.