That calculator is about right for a sea level pass for the car I had. If the car was at a DA of sea level I'd run about a 10.3 @ 132 mph with a 1.5 60ft. The video in my signature is a 750FT DA with a 1.7 60 ft starting from 1000 rpm. My shifts are pretty good though. They're about .25 seconds according to computer data acquisition
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Here's the 750ft DA pass time slip
The car has the Roush 427R. As it was with Superformance exhaust and the way the dealer set it up it made a little over 400 corrected HP at the wheels. That's why you see similar Superformace prep cars in the mid 120s mph for trap speed all the time. I changed the exhaust, fuel line, carb and intake and it made quite a bit more power with the changes to be 475 at the wheels. It was a 561 crank HP engine corrected. With that it could break over 130 mph trap speed.
FE Cobras are slower heavier and generally don't make the same power as Windsors once they're in the car.
The basic routine I've seen for stock supercars is they're not even close to magazine specs once you see them at the drag strip on an average day. I really think the new ACR Viper would be a mid 11s car in the low 120s. Stock C6 Z06s the day I ran that 10.7 were in the low 12s @ 118 or so.