2 barrel to 4 barrel

Depends on the particular 4 barrel
I had one one time that was completely bone stock, in a heavy Cordoba with 2.76 gears and swapping out only for a 2bbl 360 carb from the original (engine was a junkyard pull verified 40k mile lean burn engine, I put the original {dead} 360's intake carb and distributor on the replacement 318 in getting rid of the lean burn ones) and it was surprisingly peppy compared to other 318s I'd driven around that time..... We had "a few" other b body 318 cars around at the time.
Another one I put an 1850 vac secondary on and not enough difference in butt Dyno but definitely a difference in how much of my paycheck the local gas station started to get.... Then went to a TQ and butt Dyno power and mileage both improved.