Precursor to the 406. Solid lifters. I think only '61. The 3x2 bbl was a dealer installed option. There is a guy around here brings his to the local car shows.
The closest I got to one was our camper when I was a kid, and technically not a performance application. It certainly wasn't that one in the ad!
If I recall correctly (big if) one of the locals brought one of these back in a bright red '61 2-door hardtop while serving at Ft. Riley, Kansas. He had it in Dad's rural small town Nebraska shop to fix a miss or some such. I remember it as the first dual point distributor I'd ever seen. As a 14 year old, I thought it a fine machine.