Sorry for the delay, Skip. The RAIII (d-port) engines peaked around 5000/3500 (hp/tq, respectively). The RAIV engines peaked around 5500/3800. So on the 400, the larger round port heads and cam caused HP to peak roughly 500 rpm higher.
The 455 engines had remarkably lower peak points, but were affected similarly. The d-port 455 engines peaked around 4000/2800 (hp/tq, respectively), while the round port 455s peaked around 4400/3200. The HO's 068 cam wasn't exactly "large" for a 455, so we might speculate that the 400 rpm difference in hp/tq peaks, could be directly related to the larger ports.
For the record, I do know that Pontiac's engineering dynos ONLY recorded only TQ numbers, and horsepower mathematically calculated from it at all points.
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