I recently picked up a nice condition Winchester Model 94 in 30-30. This rifle was made in 1970 so it’s not a “pre-64”. With the rifle I got a Lyman #2 Tang sight made for the Model 94. The sight mounts with two screws on the tang. It came with a long screw which replaces the one existing screw and a short screw which will need to have a hole drilled and tapped in the tang. I have a couple of questions. First, will I hurt the value of the rifle by drilling and tapping that second hole in the tang? Second, how hard is it to do this yourself? Third, how do you make sure that you get the hole centered properly? I would imagine that the best way would be to mount the sight using the one long screw and then somehow center punch the exact center of the opening for the second screw. It is hitting the exact center that concerns me. Also, is the tang of such hardness that it can or can’t be drilled easily? Lastly, what is the thread size I will need to get a tap for? Appreciate any advice you all can provide.