Well I'm a big block kind a guy now, but I used to have the Excalibur with a stock 302. With a low rear end ratio and a low 1st gear ratio in the T5 trans that car was a "tire smoker" and reliable as all get out! Well eventually I wanted more horses, but for a guys first Cobra it was a pretty darn good call all around. I could smoke the tires till they melted and never worry about the motor.
...it was pretty much "done" at around a 100 mph though, not much left. But 0-60 was cool, a good street car.
Seriously I've found 500 horse is about as much as I want or need. It's enough to really get serious, I could see 400 doing the trick with the right gearing, especially for a guys first Cobra, man thats plenty!