Here's why I asked:
I remember using some 5356 on soft extrusion once because we ran out of 4043. The welds were pretty, with pre-heat and good penetration. However, a couple of days later, those parts literally fell apart at the fusion line. Material mis-match caused some sort of crystallization I suppose.
So, I avoided using that wire until someone brought me a casting from a traffic signal base. The 4043 wouldn't even bond. But (you guessed it) the 5356 worked like a charm!.
So when I see a casting of unknown material, I have to wonder if it is in the 4043 range, or in the 5XXXX - 6XXXX range. Based on my limited knowledge, I will always default to 4043 to start with, rather than the other way around.
It certainly work on your repair, and looks great, by the way.