What do you think of this?

A bodies are real bad about that seam comin through. Especially ones with vinyl tops cause the factories didn't finish the body work completely. I would go all the way to the metal there. You'll be surprised by rust under there, I bet. Grind that brazing out and mig it up. Clean it all backup real good with some acetone. Then get some Eastwood's rust Encapsulator and paint right over the bare metal. Then bodywork over that. Cleanliness and dryness are most important for a repair that wil last.