I recently came into pocession of a GPR that was blown up with smokeless powder.The only part I am interested in is the rear sight, it is a Lyman 57SML I will have to inlet the stock at the wrist to mount it but that is not my concern,I need some info on what front sight I will need to be in line with the new rear sight.The distance between the front and rear sight is 28 inches.Any info will be greatly appreciated ELMOUSMC