Should I buy this 440?

Latter model police pursuit 440 HP engines have that passenger side manifold. I have two of them 77 & 78 440HP. The stamp pad on top of the engine could confirm. They're still not super exciting engines at around 255hp but better than the 190hp civilian 440s of the same era.
Where did the extra 65hp come from? Certainty not just from a passenger side manifold. Serious question.