I recently bought my Ventura. When the previous owner painted it he removed the side mirror and filled in the holes (shaved). I am somewhat of a purest and I bought OEM style mirrors. I do not like drilling new holes in old steel so I am trying to find where the original bolt holes were. The backing plate on the inside of the door had filler coming through the two center holes (circled in red). I thought this was a no brainer and dug out the filler, hand twisted a drill bit from inside the door expecting it to poke through the outside but I hit metal instead. Please see the pictures and let me know what the best action is here. I am a novice at body work.