After heating and quenching O-1 (which will work fine btw), you need to draw it back to a spring temper. Test the hardened steel with a file to be sure it's fully hard, polish bright, then play a flame on it (or put it in a little sand on a thin piece of metal...piece of soda can works), and draw it through straw, then plum, and stop at the bright/light blue...there's your spring temper.
