Thanks Zagnut, I was thinking that might work.

Another idea. These probably aren't available anymore due to the lead problem, but my mother used to have plastic bags that were laminated with a super thin (spray?) of lead. These were used for storing/protecting film when it was passed through the x-ray machines at the airport. I think I still have one of those laying around to try... The shielding systems they sell for ultralight airplanes have a lead lined box, but they would be very heavy for our uses.

Also, it seems like a lot of people are running just a normal ignition wire and a resistor plug. Do I need to get shielding for the plug wire?

Thanks again,
AV8TOR