Yeah, the 60ft time is the deal breaker for times. Every .1 + or - diffrence on the 60ft is about .2 at the end of the 1/4 mile for overall time, but the trap speed will change little regardless of how good the start might be. You don't need to beat the crud out of your car to know it's potential times. Just make an easy start and figure from the 60ft time. Most Cobras regardless of power on half way decent tires should be able to do a 1.8 to 2.0 60ft with an easy start. You'll know your usable power for the particular air by what trap speed you have and the weight of your car if you use this calculator.
http://www.prosystemsracing.com/calculate.html
So maybe on average nice day a 2700 lb race weight Cobra with 350 corrected wheel HP(basic 500 HP engine) on a 1.8 60ft might be a high 11 @ about 118 mph.
The pass in my signature was a 1.7 60ft starting from idle on Mickey Thompson drag radials 275/60 15, 20 psi, 475 corrected wheel HP. About 2550lb race weith with and the air (DA or density altitude)was about 700 or 800 ft