I'm from a different era, 6x2 wasn't uncommon, in the late 50's threw the 70's. I feel in love with multi carb engines (more than 3) in 1959. I lived on a rural road with a straight stretch of at least 1.5 miles. One day a '32 or '34 Ford coupe, made a run on my street. It had a nail head engine, with 6x2's and I'll never forget the sound of the carbs, as it pasted me.
In those days, most where called "log" manifolds. You could even by kits, with a piece of round tubing, intake flanges and tubing, to fit the flanges, then weld it together.
In 64/65, I had a 410 MEL, I bought a 6x2 manifold for it and two sets of 348 Chev tri-powers to put on it. I was going to put it in my '60 Galaxy, to replace the 352 but, I got drafted in '65 and while I was in the Army, my dad hauled the engine off, for scarp. I kept the manifold for a long time after that but, threw it in the scrap pile, at work, in '76 when I moved out of SoCal.
Did Jay have that 6x2 ported in his test? If not, I bet a good porter could take it up a notch or two, on the manifold test scale.