JB-Weld would most likely be a forever fix.
I like JB-Weld but have always used that old messy brown hardening type Permatex on Freeze/Core plugs with no problems. I clean the hole area with 180 grit emery paper to get rid of the loose rust. It is best if you can see the bare metal. Degrease with brake cleaner before application of sealant.
If you decide to replace all of the plugs solid Brass (not plated) Freeze Plugs last longer (at least on gas cars).
I have replaced one with Brass while the others were steel with no problems but I don't want to start an argument concerning Electrolysis and dissimilar metals; use your best judgment.

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84 300D, 82 Volvo 244Gl Diesel