Sure sounds like some sort of receiver sight set up. Some require wood to be cut, some don't. Addition of receiver sights is not at all uncommon on sporterized guns. What type of sight is on it now? What model and serial number? What barrel length? Many of these sporterized gun were cut to carbine length, some are real carbines. This could affect the desireability. Does it still have a wooden handguard on top of the barrel? Have you shot it yet? They are addictive, as you will learn.