Any 455 wakes up with a cam and intake swap. The right head on it makes it even better. There is no dog when it comes to 455s, only not enough airflow being allowed through it. The bottom end is the same on all of them except for the SD.
A pair of SD heads will make it run pretty hard despite the 8:1 compression they had. Same with 71-72 HO heads. Its all in the heads, the bottom end is essentially the same.