Howdy other Robin,
Modern chain tensioners enable way too much force to be applied. I did myself break one. I have seen many with them broken. I have not seen one that I could detect having been repaired.
I have always felt that there would have been an approved repair and that is what I was hoping someone might post, as we have some REME folks on here.
For my money, as someone who does a lot of repairs on the farm, I would want to cut off the whole plate onto which the loops are attached and make sure the new loop goes right through that plate and gets flush welded behind as well as on the front side around the bar stock.
However that is a lot more work and I think that your way would be what would be used but with a two pass weld enabling a root pass with 100% penetration to be used.