Why not a 413 ?

383, 400, 426, 440.... but why not a 413? I've never owned one. They advertised 350-380 hp and 450-485 ft lbs of torque from the factory. Would it take much to get 450 hp and 525 ft lbs of torque on pump gas??? I'm looking to learn..... carry on, and thanks in advance
:thumbsup:
there is one on b bodies for $350.00