i would go with neither muzzle break, or porting, unless you are shoting a 505gibbs or larger, you really dont need it ( ive shot the .460 wby w/o muzzle break, its gives you a sharp rap on the shoulder, but its well worth it when hunting), i would not get anything ported/ brake installed because of the ear splitting report, i much prefer a well made stock, like that on the A-Square .577 Tyrannosaurus, which (with no muzzle break) is less than that of the .460Wby, just my 2 cents.
ken