Changing from positive ground to negative ground will have some implications. You probably will have to get a new coil...one oriented differently. The positive ground coil will have the windings going in different directions in all likelihood. I've been also told the voltage regulator could need to be changed, but I'm not positive about that. Other than those two things, offhand I'm not certain the electrons will care much.
As for non-resistor plugs, you can use those only if you wear a hat made of tinfoil at all times. You should also sleep in it. Then the radio waves at NASA will be ok. Seriously, non-resistor plugs are still made. Last I looked, they were costly. As I recall, resistor plugs were simply a better match for radios at first (since at that time nearly all vehicles came with them) and later they were more friendly to ECUs and other vehicle electronics. You need to understand non-resistor plugs set up a very high degree of interference (electromagnetic interference) and will play havoc with other vehicle electronic devices.
