Any reason not to JB Weld the radiator bracket?

One thing to remember...JB Weld is a structural EPOXY. No matter how you slice it, epoxy is not welding or silver soldering. I don't care if your Uncle Tony patched a cracked block with it, it's still just a 2 part epoxy and subject to the same failings of other adhesives.
I agree with the idea to take it to a legit radiator shop and be done with it. Helluva thing to have it bust loose on the open highway.