Not to ding anyones opinion here, but I am noticing that the guys who hunt where elk live are saying yes, and the guys who don't are saying no. Having lived and hunted where elk are abundant all of my life, I know a lot of folks who have done it with less. Not reccomended mind you but it has been done. Lighter set ups demand perfect shot placement. Nothing is worse than wounding and loosing an animal.
I hunt with a 55 lb longbow and can tell you that a 575 grain arrow will work just fine. I will also say that shooting at 25 yards and under, a much heavier arrow will penetrate far better, and won't have that much different of a trajectory.
My elk arrows are 684 grains and optimized per the Ashby reports. If your keeping it at 25 yards and under, I would set up some heavier high FOC arrows for the hunt.
The key is to stay calm, keep your shots at 25 yards or less, and don't take iffy shots. Slighty quartering away or broadside are the only shots to take. Make sure your arrows are tuned perfectly and don't get excited and take a long or bad angle shot. Elk are tough and will travel for miles if hit wrong. Hit them in the boiler room, and they will run 60 to 150 yards and expire, and then fun is over and the work begins.
No 2 inch wide, super steep angle heads. They will be stopped dead by a hard hit on a rib.
American Indians killed millions of elk with 30 to 40 lb bows. You can definately kill one with your set up.