A good friend gave me his father's Ranger 103-2 bolt action rifle. It is in like new condition. From what I have read, it was made by Marlin for Sears. It is pre-68 as it has no serial number. The receiver isn't grooved and it has the tinyest rear sight I've seen. Apparently folks had sharper eyes back then. Any suggestions short of drill/tap of the receiver to help out my fading eyes for this rifle?