For the most part, the quickest Pontiacs from around 1959, thru '66, have had more than one carb. The 421SD engines had 2 AFB's. Quite a few cars came with three 2-barrels, which Pontiac called Tri-power. I think Tri-power came in 370, 389, & 421 versions. Not sure about any others. I'm not a Tri-power expert, by any means. I'm a Q-jet guy.
In '66, the GTO could come with a 389 Tri-power. I suppose the most famous was the Knafel Pontiac car, I call the "Trophy Car". Knafel actually had at least 2 of these cars. Below are pics of their 2-car rig, with both cars aboard.
Royal Pontiac also raced this model. And I'm sure there were probably quite a few other Pontiac dealers that sponsored 1. No telling how many '64-'66 Tri-Power GTO's were raced, all over the country. From what I can find, it looks like most of 'em ran either B/S or C/S.
Currently, I only know of 2 Stockers that still run Tri-power. Bob Michael has a '62 389 GP. And Norman Warling has a '62 Catalina, with that same engine. Norman actually tried a 421SD in his car for a race or 2. This past weekend, with the Tri-power 389 engine, he was #1 qualifier at the 1st race & #2 qualifier at the 2nd race of the div 6 doubleheader.
https://www.dragracecentral.com/DRCS...r2021#indextop
https://www.dragracecentral.com/DRCS...r2021#indextop