I know a SO CA SS drag racer that had one of the special lightweight 1966 R code(? ) 410 HP 4 speed Fairlaines that he raced in SS/C and later in SS/B. He ended up swapping heads on that motor over the years several times going from the original medium riser single four barrel combination to the high rise heads with the factory dual inline 735 CFM Holley carbs and again to the tunnel port heads and intake, the car ran faster with the high riser heads than it did with the tunnel port heads and intake He worked for Valley Head Service at the time, he was the machine shop manager and found out that the pushrod casting in the tunnel ports heads restricted the head flow enough so the other heads flowed better, this was in the mid to late 1970s
Siamese intake and exhaust ports are not the best way to make power on any race engine