The only instant kills guaranteed are the brain and front spine shots but they're both small targets. I would say the the best option is probably the shot that breaks both front shoulders.

Shoot them where the neck meets the head.

They'll be dead before they hit the ground.

best place to shoot a whitetail??

As close to your pick-up as possible.

I have never shot a deer with a .270, but I doubt if one would run more than 100 yards if it was shot through the lungs (less if through the heart). I have tried dropping them in their tracks by taking a shoulder out, but the deer still managed to run to the bottom of the hill.

The plain old heart shot. No deer will live through a .270 through the heart; it's instantly converted from live to dead.

I hunt with a 270 win and im relatively new to deer hunting and i was wandering wheres the best place to shoot for a INSTANT kill?( theres alot of private property near i hunt and i cant hunt it)
thanks