You are over thinking things. According to federals website 180g SP will drop -15.3" @ 300 yards with a 100 yard zero. 150g will drop 13.6" over the same distance. The difference is less than 2". You'll have about equal problems compensating 15" vs 13" when holding crosshairs over an animal at 300 yards. Keep in mind range estimation gets harder the longer the distances involved. A miscalculation of 50 yards will easily wipe out the 2" difference as both bullets start dropping really fast after that.
(edit) opps I should actually read the rest of the thread, I see your already on board. Zero for 200 and you'll be good. Just get off the bags and shoot like you would in the field.