I did a quick calculation based on VERY BIG GUESSES at the dimensions and it looks like the tang cannot handle the side load very well. Taking an extreme case where the anchor rode is perpendicular to the boat, the yeild strength would be less than 1/4 of the SWL of 3/8 BBB chain. This means your attachment point will fail well before the chain. You could make it much stronger by welding a cross piece on both sides near where the shackle hole is.