Yooper has a pretty good idea of what's up. Basically it's called compromise. And you should shoot an absolute minimum of 350gr. More doesn't hurt and can be benefical. Considering your draw a lighter arrow is going to make the bow shoot louderbecause of increased vibration. This inturn can lead to some kind of bow failure. Consider it a pitfall of having such a long draw.

Think about this. Your setup is plenty fast enough and is prducing tons of kinetic energy. If it's quiet and you can draw the bow easily then it makes for an ideal setup. I'd be happy.

If you're so inclined to investigate you can log onto Gold Tip's website. Look in Products/Build Your Own Arrow. Look at UL 22 series arrows. Preferrably Pro series for your length. Work up an arrow and see what it comes out to.