The previous owner of the heads said they had been flowed and should support 550 HP.
That chassis dyno is showing what looks to be 550 HP at the crank. If you lose 20% that is over 100 HP.
Your car almost runs like my fish did with the 416 (500 crank HP, 3050# with me in it, 3.91 gears). The ET and MPH are just a bit slower. IMO the other guy on that slip shoulda been a lot faster at the 1/8th based on his 60 and ET. He was doing something wrong or sandbagging.
