All the arrow manufacturers that I know of have a chart for picking the right spined arrow, or close to it. From experience I can tell you you could be shooting a 500 spine. The arrows you are shooting, although on the stiff side, should work. The main difference between them and the 500 would be that the 500's are lighter in weight. Not sure you want to compromise any weight though.

With carbon arrows you will find that a slightly stiffer arrow will fly better, especially with broadheads if you have some sort of breakdown in form, such as in a hunting situation.

Id say that if your arrows are flying well for hunting then go ahead and use them. If you want to try some 500's then that's what the rest of the year is for.