[Candle]

I cant say I know much about the 427,428 or the cam that is right for you. You want to leave the line hard and top out fast without spinning the rear tires. The best key to this is to use a rear end gear ratio near 4:10 to 1 or greater and positive traction. This can also be helped if your drive line can hold the pressure when the clutch is dumped at approx 3000 rpms. With a stock 427 producing 425 hp @ 6000 and 480lbs/ft @ 3700 this can produce rear wheel spin, expecially with 3:50 to 1 or lower rear ends.
If you know your head flow data, compression, stroke, bore, and cam data you could use software like Dyno2000 by MrGasget to come up with approximate data for your specified needs.
Although most frown at using an automatic in a cobra this may be the route to go for jumping off the line. Not for me I would have to say.