I shoot a 70lb set up and my arrows are carbon rebels- 5075, blazer veins, and 100gr. sonic heads. Using the "Front of Center" formula my arrows come in at the 8% range. The formula says that carbons should be in the upper area of the acceptable weight dist.(7% to 14% I beleive) for proper Front of center. What if anything should be changed if my arrow flight looks great??? Are these the proper spine arrows for 70lb??