JB weld would be fine but good to use some bridging as well in the form of steel mesh
however best of all is hts2000 alloy braze at low heat, just need propane torch or oxy
but as long as you can get enough heat from propane setup thats all you need.
I saw a thread on a RB25 box for SR20VE in japanese using this Brazing and seems
to be better than TIG for the amount of input, time and finish couldnt see final joint

https://www.youtube.com/watch?v=RCrixbXz4rc