Filling the seam with brass is an idea but getting it smooth is the problem. If your metal is perfectly straight and all you have is the brass you can remove the excess brass with a 3M Roloc "surface conditioning" disc. It's a neat tool and will remove the softer brass while leaving the harder metal untouched.
But welding it is usually going to cause some distortion that needs grinding to true. So what you have now, I don't know.