I’m not a fan of JB Weld myself but it could work on something like this. What I might be concerned with is the timing chain cover which is cast aluminum. With age and old coolant these small block Ford covers were prone to leaking due to the aluminum rotting out where the coolant passages mate against the cast iron block. (Generally on the passenger side of the engine.)
I wouldn’t want to get too deep into fixes until it’s known that the cover is not going to be a problem and the entire shooting match all has to come apart again.
(The covers are enough of a problem that a local salvage yard here stocks new covers at about 40 bucks each.)