The standard CR45LC front sight is a Marbles 57W which is .570" high, it's been reported to be a problem before, best advice other than a taller replacement front sight which I didn't find, is to use a fine sight, that is to bury the bead in the rear sight notch and hold 6'Oclock.

The only other dovetail sight H&R offers is the .584" 17A Lyman globe sight for the 45-70 BC, you might PM Brian56 and see if he has a recommendation, I'm sure he's dealt with it before.
Tim
On second thought, seems to me the problem before was it was too tall and shot low, are you sure you're holding the rifle well? Mine has terrible muzzle jump when shooting on bags due to the drop in the stock which could account for the high POI.