The six pack intake will kill off some top end power on a big motor like that but if that is what the guy wants then who cares.

A good single plane intake with a big 4150 carb will make more power on the dyno than a six pack setup but it might not matter depending on who the guy is and how he drives the car.

I'm going to put a six pack on my low deck 512 even though it will kill some top end power. I just like the way it looks. I'm assuming that I'll be able to tune it but I'm sure it will take some work.