Another Mopar Off My Bucket List - Barracuda Fastback

Most spray-can clears will destroy decals, including vinyl stickers. Sometimes not, if applied in very thin coats with plenty of time to dry between coats.
However, if you use a catalyzed 2-part urethane clearcoat, it is usually safe to apply over nearly anything. This would be the same clear "paint" that is used as the final stage of 2-stage paint jobs on real cars. On model cars, I've used it over enamel, waterslide decals, alcohol based lacquers, and water based acrylics with no ill effects. But the stuff is deadly, so if you decide to use it get the correct breathing apparatus.