Interesting that they copy the Holley 1920 design almost exactly,
They didn't, actually. That same basic style of Holley 1-barrel carburetor, with the rectangular float bowl facing front and the float hung from the starboard side, dates back to way before the 1920 came along in 1962. It was in use in the 1904 (the glass-bowl "Visi-Flo" carburetors of the '50s) and others. Numerous models and variants built not only by the Holley mothership in America, but also by subsidiaries and licence holders scattered all over the world. There are quite a few pretty fundamental differences between the current-production Argentinian carb and the 1920—the separate throttle body is more 1904like, for example; the airhorn configuration is different, there's that screwy (zing!) adjustable jet, etc.
variable throat area ("slide") which is what I recall was the automotive Predator carburetor's claim to fame
Long-long before the Predator existed, variable-venturi carburetors were commercialised in huge numbers by the likes of SU and Zenith with great success, and by Ford with miserable failure.
It looks like the bowl
might be vented via that small transverse hole in the casting, just aft of the the top bowl screw. There also
might be an internal bowl vent we can't see from this angle, but without the angled draught tube we're used to seeing on the American 1920 (and most other carbs—it's there for a good reason, too, which would make its absence problematic).
It appears to have a sight glass to verify the fuel level, which is great.
No sight glass; that boss you're seeing on the float bowl is for an externally-adjustable jet. Conceptually that strikes me as roughly 50/50 benefit/drawback, but I have no practical experience with this implementation of it.
In the past, you had to remove the "economizer" (3 screw thingie on top) to measure the fuel level.
You still have to do that on this Argentinian carb.
That part actually enriches the mixture under certain conditions, which I think makes it equivalent to the "power valve" in 4 bbl Holleys.
"Economizer" was just Holley's cutesy name for the power valve on the 1920 carburetor.