i'd drian it, drillstop te crack and weld with a cast iron type rod.. preheating local area with propane torch.. especially burning oil ot of the crack.
then peen it while slow cooling and still applying some propane heat.
that , if done correctly will be stronger than brazing, and leak proof.
repalcement would be my next choice.
while not often.. I have done some cast welding.. so far.. ( knock-knock ) with good results.
including an Noil pan, and a 3pt pin boss on a rowcrop and a cast loader bracket.
so far.. all holding under weight and regular use.. not being babied...
best of luck.. jb may stop the leak for now.. but that crack will run and flex and that jb will be a temp at best fix...