I am restoring a 1965 Chevy II 2 door sedan . I bought the car site unseen . (internet ) The car was primered And is solid everywhere. Calif.Car it appears to have some pitting on the roof and trunk lid from rust , it appears to of had a tarp over the car and it sweated an caused it rust under the primer . How should i Attact this problem ? The car is going to be totaly restored and i dont want this rust to come through the new paint in a couple of months ! any suggestions?