Its possible..
I've used those cheesy "Trans-Dapt" 2 to 4 barrel carb adapters..they work,but you have to be careful to be sure the additional base gaskets seal at all locations..there are so many holes in the adapter,some allow vacuum leaks to occour where the gasket does not cover them completely..I had to make a sheet metal "gasket"plate to use on mine,a bit larger than the carbs base gasket, to get the gaskets to seal 100%...
I put an Edelbock 600 CFM carb on my van's 73 307 motor,which had the tiny 2 bbl stock manifold for a 2GC Rochester carb,using an adapter..it ran ok,but the 4 barrels were a bit too much for it..it ran great on the primaries,but it did not run good when you floored it..it actually felt like it slowed down some!..my 305 in the 79 C10 now has the same carb on it,on a stock Q-jet 4 bbl intake..it runs about the same,so maybe the carb's secondary's are not jetted right ..I've had others vehicles with 4 bbl carbs adapted to a 2 bbl intake,that ran quite strong--hardly could tell the difference between it being "adapted",and having a real 4 bbl intake--at least on daily street driving..
I'd put another 2 bbl on it,since gas prices are insane,and will likely only get worse..a Q-jet would give better mileage if you keep your foot off the secondary barrels though..a Chevy version of the 2GC carb should bolt right on the Buick intake,and it'll have the stud for the detent cable if its off an automatic that had the TH350..or you could jerry rig one on the Buick carb by using a bolt and double nuts,or welding a stud pirated off another carb to the throttle lever....your carb probably only needs a new float and a jiffy kit,unless its cracked..
