My Finished 642 and gear.

[mmc45414]

Very specifically now, what would be the best kind of file for this?

I am sure if you bought this:
https://www.amazon.com/Needle-HIGHES...s=needle+files
and maybe added this:
https://www.amazon.com/SE-73810DF-10...s=needle+files
you could get it done. I have an old school set that my dad had for years, but it really isn't that complicated. I would recommend putting tape over the stuff you do not want to scratch.

I would also recommend these:
https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1

My impression is that the standard dot XS sight is the way to go for compatibility with the rear sight notch and POI issues. True?

The small dot fits the slot better, but I have both and for what it is I like the bigger one: