Brett, What you want to do is expose as much of the rusted area as possible,strip all the undercoating off and neutralize the rust with something like POR 15 or Conquest thats about all you can do.I have spent 20 hours on the chassis of my cs doing the same thing.I will restore the body completely in 2 years and this should tide me over until then.I am lucky because although there is some rust the A pillars are not the horror they can be in these cars.