If you can get your bullets launching at the same velocity, then they will have very similar ballistic paths...not necessarily identical though (because of bullet shape, ballistic coefficient, and a hundred other small details).
However, I worry about over-pressuring the 180 grain loads to match the velocity of the 150 grain bullets. There is normally about a 200-300 ft/s difference between the two.
Unless you are shooting at ranges in excess of 300 yards, the normal difference between the two is not really that significant.