Not sure how common this is among the guys running Rocks, but I saw something today that seems like a good way to run leaf springs: two spring plates, one welded to the square tube, and the other on top of the spring pack. That way, you have two holes for your center pins, and the hole pattern will be the same. Just lay some weld on it, and call it done. I've seen where people will weld a long nut to the tube, but that seems like it might not be the most durable thing in the world, because the bolts will have a tendency to flex, and you have to be extra careful of where you weld so that your spring plate on top matches up with the nuts.
