This is a highly technical question which, whilst it might be interesting to rhinoplasty surgeons, is of little value to prospective patients. Rib cartilage is a very useful material for major reconstructive work or if septal cartilage is not available. If you cut a strip of it lengthways, it does have a tendency to bend (try doing the same with a carrot and you'll see what I mean). You can get round this by using cartilage from the centre, rather than the edge but, failing that, you can use to slightly warped pieces and have them facing each other as spread grafts so that they cancel each other out. This is a useful trick but is by no means a guarantee that late warping will not occur. Unfortunately for you, the best piece of advice I can give is to find "an experienced surgeon" who knows how to handle the cartilage, cut it up judiciously and select the right pieces. I hope that gives you some insight