Hey, that turned out great! Nicely done.
To answer your questions, I use this pivot lap from USA Knifemaker to shorten all of my pivot barrels and bushings:
Pivot Lap I insert the pivot or bushing and use a disk grinder or piece of sandpaper on my flat plat to lap the piece down to size.
To shorten screws I have a jig made from a piece of hardened O1 steel ground to the right thickness that has tapped holes through it. In fact I made a new one this last weekend. I do the same thing as with the pivot lap and insert the screws and grind off the ends down flat with the jig. The one I made can trim 3 dozen screws at once. In the beginning I did have one made from a piece of 0.050" titanium with a single hole tapped. I could advance the screw and trim little amounts off until I got the right length.