Don't forget cutting oil for tapping. In a pinch any oil or thin grease will work. I think that screw position was pretty short depth, but if you seize and snap a tap in the extrusion it will be a shit time even got a shallow home. I wanted to put the picture of a tap snapped flush with one of the end holes but I guess it was on my old phone. I got it out with a screw extractor but it was really hard to drill the pilot hole, and didn't seem like it would work at first.