Those are impressive numbers! Shafts are often underrated IMO. With your level of skill, you have a lot to gain with an upgraded shaft. In addition, sometimes stock factory shafts are wrong. It may say stiff, but may not be accurate. Also, it may not be spined (where the seam of the shaft is aligned properly), or have the correct flex point, weight, or even length!
A lot goes into custom club shaft fitting. With that being said, the price of the shaft doesn't always reflect the quality. Some shafts are upwards of $300.00. The key word is custom. What will work for you may not work for me.
I'm anxious to see what numbers you get if you reshaft it!