hey which intake is better squarebore or spreadbore and carb size for an engine that is bored .60 over and sleeved at .40, bigger cam, etc etc etc maybe 450 horse's pushin, thanks

 

Carb size - general rule of thumb is CID x max RPMS / 3456. You need at least that much carb. A little larger if you're using a dual plane intake.

Intake type - if know you'll be using a squarebore carb, get a squarebore intake. If you'll be using a spreadbore carb, or might be, get a spreadbore intake.

Obviously, the information you provided isn't enough to get more specific. What you'll be doing for cam & heads is also important, as is what you plan on doing with the car when you put that engine in it.