If the fuel bowl is severely corroded then you might be better off with a new new carburetor as the fuel bowls from Briggs are ridiculous now. The 796778 bowl list for $112 with my cost @ $90 but I was lucky as I brought 5 of them back in July 2020 for $30 each before Briggs jacked the prices 3x. Now they are just a little cheaper than a complete carburetor but I see Briggs has also jacked the carburetor to $182.50 list so the two are separated somewhat price wise again. Back last year they were only separated by $10.
Now if you just wanting the remove the corrosion from the fuel bowl to see if it is still usable then a little sulfuric acid (battery strength) will do the job but bowl would need to strip down to just the aluminum bowl. No steel, rubber, or plastic allowed as the acid will destroy them. Caution toxic fumes are produced so this an outside job. Also this is for less 30 minutes or aluminum damage can occur.