360 to a 408 how much quicker

so i gues its all with tuneing and having the right parts.
I have magnum heads
a xe274 cam .524 lift with 1.6 rockers
kb107s 10.6 compression
4.10 gears
crosswind intake
bigs Stage 5 750 dble pumper

and i just want mid 12 to low 12 until i get the 360x head or edelbrocks


and what is on your car to lighten it up besides oils and wheels