Sure it could be done , IF, that is what you so desire is to get it back to original . But like was stated , that rear sight is gonna cost ya !
That peep is 100 times more accurate than any open sight is ever gonna be though and is a great addition to any lever gun .
I look at your gun as a Customized Lever Gun , not a mistake that needs correcting . You have to undestand one thing , even back in the day there were people and even gunsmiths doing upgrades to thier arms or other peoples arms to customize them to thier own liking , or to the customers own liking . So your upgrade is not unusual or abnormal to see , and is really a nice improvement over stock . JMHO