Well, in my personal opinion I think a lighter set up would prove very constructive for elk with an efficient broadhead. I shoot 60 to 65 pounds and set up on my first elk hunt this year with a 625 grain arrow at about 10 gpp. Now that I have been, I would much rather have had 9 g per pound for a flatter trajectory. I got within 35 to 40 yards of two cows and would've been able to take a shot with accuracy had I had a lighter set up.
After dressing my buddies mature bull elk out i'm confident that a 500-ish grain arrow would do very well from your set up with the right Broadhead. I think most set ups would do well on elk and less you hit the shoulder, then you're screwed regardless of what your set up is.