Insights? nope. Not much to them. Pretty basic machine work. The only appeal to the factory blocks are the fancy contours. I'll never buy one again.
I made one from 11L44 barstock and a couple from raw forgings I bought from Garrison a few years ago, and they work.
I made the 1144 about 0.003" oversize on the barrel by accident, but with the setscrew underneath and opposite the gas port I see almost NO gas leakage. I probably could have made the barrel hole even larger.
The "adjustable port" is just a pointy set screw inline with the gas port hole to restrict flow, inbetween the barrel and the gastube.
Next time I am home I will drill that barstock gas block for a setscrew and drill out the barrel gas port from 0.071 to maybe .093 (300 whisper build, pistol port gas location). I think I will add in a nylon faced setscrew at right angles to add drag to the "throttle" setscrew.