With a 500 gr arrow,how much of a actual draw weight would be able to punch through shoulder bone?

Why are you wanting to shoot through a shoulder bone?
To answer your question and this is for most any animal, it will depend on the broadhead you use. but aiming and hitting were you aim right behind the shoulder area is the place to shoot.

I don't think there's a bow made that will push a 500 grain arrow through a solid shoulder bone hit on a mature elk.

I wouldnt want to shoot through the shoulder, I was just wondering what would happen if your shot was off.

If you hit the bone straight on, the broad head would likely penetrate the bone minutely and the elk would run off either dislodging the whole arrow or breaking the shaft off. Even on the thicker portion of the shoulder blade, penetration would be limited. The thinner portion of the blade would be penetrated easily, but you would loose a lot of kinetic energy.

You wanna be missing that shouldera and You wanna be using a heavier arrow than 500grn, If you're shooting Trad I'd go for more in the region of 600grn, with a good solid 2blade like an Outback Supreme or STOS and even a 3blade Woodsman. I'm shooting a 54# Longbow, with around 590grn-615grn depending on which BH I use and that will pass clean through on a behind the shoulder shot.