2" at 25yards should be about 2 1/2" high at 75yards, Rich.
That's an estimate using .75" height for top of the front sight above the centre of the bore, along with .8 for the BC and 1,400fps for the 85gr. 2F powder charge. Higher velocity or higher sights will, of course increase the impact's height.
As-is, it should be zero'd for 100yards. Holding 1/2 sight height in the rear notch instead of level, ie: "holding a fine sight (or bead)" should give a 25/50yard zero. This is normal 'holding' for iron hunting sights - even as described in Forsyth's book when he spoke of the Kentucky rifle and how it was aimed. Holding a fine sight for close in shooting and a full (level) sight for 100yard shooting, showing they had a long point blank range with one set of sights.
He compared these to the English conical ball shooting and fast twist round ball hunting rifles of the period needed sights for both 50 and 100yards to be able to hit with due to their excessive elevation requirements.