Unported head quickness?

1965 dodge coronet, bone stock 1965 383 "original motor to the car"
.528 mopar solid
Stock 2463200 casting heads"i read they are same as 516 heads
Mp dual springs
Holley 850 ontop if a street dominator
Mp distributor 38* total timing
1 3/4 headman headers
727 home built rmvb with 8" treenaster flashes to about 4300
Stock suspension with springs clamped and snubber
4.56 gears
275 mt drag radial at 3500lb went 12.65 at 104
Msd had a 6200 chip and i was on the rev limiter about 30 yrds before the traps