You may have him by 200lbs or so but i have a feeling that an extra 60hp could make up for that. It'll really be a driver's race. Also he's gonna bring on the torque a lot sooner than you, which means beating you out of the hole if he has traction.
Speaking from experience, if you can drive your machine you will win. My old man has an 03 anniversary termi that dynoed 430 on the same dyno I put down 420 in my 91. I beat him every time in the quarter because the 5.0 gets out of the hole so much better. I have done it time and time again resulting in my old man giving me the bird BTW if the roles were reversed the old man would probably whoop me, meaning he can drive like an SOB, so his cobra doesnt need a driver mod. Hes a better driver than I.