you could probably go up to an 18" rim and tire combination on that car and get away with it. My 71 skylark has 15" pontiac ralley wheels on it with 75 series tires and they don't rub at all.
American Racing offers quite a few rims which have a nostalgic "old school" look to them in sizes ranging from 15" up to 20". If you can find a tire and rim dealer, they should be able to answer all your questions.
Bookmarks