That needs to be PROPERLY welded. It may need some metal replacement but should at least be stripped to check for other cracks under the paint. After it's welded you may need to heat it to equalize the welds.
It may be something you would have a local weld shop; preferably one who works on race cars for two reasons. They will understand the importance of getting it right and....you can monitor it. If a crack develops again, if they did the welds they can go back and fix it.
I would have no problem doing this to my car, where I could keep an eye on it so to speak.
What ever you do do NOT BRAZE IT!
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