Morning All

I inherited a Savage Model 3D single shot .22 bolt action rifle from my father. The firearm is still in very good condition and shoots like a dream. I am currently contemplating if I should add a cheapish scope to the rifle for longer range plinking out to about 100 meters. Now my question is what is the value of these rifles these days? I couldn't get a lot of info on this rifles, never mind a clear estimation value for them. Is it worth modifying the rifle and adding a scope which will require a gun smith to drill & tap holes into the action to have a picatinny rail fitted or is it better to keep the rifle stock? I do not really want to mess up the rifle if it might be worth something later on in life for my son. Hope to get some advice from you knowledgeable hobbyists.