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:
I ran a combo on desk top dyno for my buddy the other day, give me a second and I'll find it.