I have run dual 44mm IDF carbs on a 4bbl intake. The IDF is a downdraft carb, so the adapter is more streamlined & probably flows better. Engine made 30 hp more on the dyno than a 4 bbl. Also performed well at the dragstrip.
The air 'filters' on the carbs in the pic would be very restrictive. If you want to go Weber, try Redline in Hollywood, Calif.
