Why are you replacing needles? Are they broke or worn out? Those needles are made of maleable iron and can be adjusted to original curvature in a press if they are just bent. I've also seen them welded/brazed after they were broken.
We took them to the dealer's shop and had them bend the needles to the same curvature as a new needle whenever the needles got bent - never did buy a new needle in all the years we had that baler.