The foc is determined buy the arrow, not your bow set up. The arrows you are shooting are fairly heavy for a carbon shaft. I'm shooting 74 lbs with a 450g arrow so you're a bit heavier then I with about 20lbs less pull.

If you're happy with your arrow flight I'd leave it alone. I didn't check the chart but lighter arrow might not hurt you. If you choose the same head weight you'll likely end up with a little higher FOC.