Use 35 yards. At one of the clubs that I've worked at, all of the rifles that were sighted in for deer hunting were sighted at 35 yards, with a .270 you should be less than 1/2" high at 200 yards if you sight in at 35 and your second crossing will be about 210 yards.

Other factors come into play such as scope height above the bore and different loads used, bt sighted at 35 yards will get you right where you want to be.