Since I had previously identified that the initial opening in the leading edge of the wing wasn't large enough for the stall warning vane, I started by marking out the new dimensions with blue tape and marker. Then I used needle files to carefully enlarge the opening by hand until it reached my desired dimensions. Reinstalling the stall warning assembly with screws now produced the desired placement within the hole. I also visually checked the angle that the stall warning vane made with the nose of the wing and it seemed to correspond with what the instructions were recommending.
Then I use a step drill to enlarge the punched holes in the underside of both the left and right skins to 3/8" for the tiedown hooks. This was followed by a 3/8" reamer and a little bit of deburring around the hole opening on both sides.