my concerns are without knowing exactly what alloy the cam cover is made from it is impossible to specify the correct filler wire, also due to the welding process it will have locally annealed the area, resulting in hard bit-soft bit-hard bit which is very likelly to crack, although i would guess that it would litrally snap the weld and not the cam cover, ideally you need to know exactly what filler wire then have it heat treated after weld.

my suggestion would be to machine two holes that run from the inside of the camcover into the main body of the support and then screw in a couple of counter sunk bolts