Back when I owned a body shop, we used a product called "Aluma-Lead" that was mostly powdered aluminum in some type of epoxy binder. We used it to fill in rotted rear window channels on the mid-70's GM products by sandblasting the rusted metal, backing up the fill with cardboard, and spreading the aluma-lead about 1/4" thick into the channel. I don't remember a repair coming back because of it coming loose or leaking. I don't know if that product is still made, but Devcon Epoxy Aluminum and Eopxy Steel is still available. It's industrial-strength metal repair, MUCH better than J-B Weld.
Jerry

"It is better to be silent and be thought a fool than to speak and eliminate all doubt!" - Abraham Lincoln
Cringe and wail in fear, Eloi- - - - -we Morlocks are on the hunt!
There is nothing noble in being superior to your fellow man; true nobility is being superior to your former self. - Ernest Hemingway
Love your enemies and drive 'em nuts!