I stay in the 9grn to 10grn per lb of draw wt. My longbow at 55# shoots a 500grn total arrow wt at present with a 75grn brass insert & 125grn head up-front for 200grn up. It's the perfect combo of speed & penetration. I also tested 400grn -- 600grn -- 700grn arrows. None out did this wt. Works for me!
Hawker, your present arrow is right at the 9grn per lb wt. it's a bit bordering the light side for 60# if of course you actually pull the full 60# -- Will it work, yes! I would say that 575grn or there abouts would be right at your bow & arrows peak energy output! The arrow wt can only store what energy your limbs supply, too light or too heavy & the energy is wasted, we look for that aprox "just right" wt from both!