I like the idea of tapping the tubing instead of weld in bungs but then you need a tap and i can see that whole process being difficult. Your setup will turn out nice.
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Weld in bungs are the way to go. It's so much stronger, looks cleaner, and it's 100x simpler
As for your mount, I think you need some more bracing on the backside of it and box it in. Other than that, it looks good.
I personally would have incorp. the upper mount into the frame more and shortened the track bar. There's a lot more force on that mount than one would originally suspect. I would have also welded it to the frame as well as bolted it. And I would have made a gusset on the lower mount (on the back of it). Other than that, it looks great.