Mdman352 You have not given any other specs on your car. This leaves a larger than normal playing area. For 90% of the people on this forum a good running 390-452 will more than enough power for you to scare the crap out of you in a Cobra.500 ft of torque and 450-475 REAL HP at the rear wheels is about all a cobra can handle in a safe way. Cobra, like others here have said is NOTHING like any other car you have driving. No ABS, No Traction control, No Power Steering in some models, No Power Brakes.
I have had a 452 motor in my car for 8 years. 370HP and 460 Ft of torque with a 6K limit for the rpms of this motor. My car would running 12.50 in the 1/4 mile all day long on pilot street tires. The new stroker motor is a 600 torque, 500+ HP motor with the same drive train. I have to change the power band to stop the stupid tire slipping when driving from a stand still. 3.31 gears is too much for this amount of torque. Going to a 3.07. Changing the trans first and second gear to a lower one in the 2.80's. The cam in the motor will also be advanced 2 degrees to remove some bottom end power. FORGET the HP numbers, torque is what moves the car NOT HP. That's for top end running. Build yourself a nice motor with a 550 HP and 600ft of torque with a 6,500 rpm limit and hydro roller valve train. This will give you years of fun and just basic maintainance. Look up Excalipers old threads with that 427 animal he built. He re thought his motor and came up with a streetable motor that was easier to drive, better MPG, could idle for more than 2 minutes, and was just as strong and fast as the race motor. Build yourself a 482 motor with a 630-650 hydro cam shaft and good heads. This is a great build and works in a lite wieght cobra. You will be in the 600 club and still be able to drive the car without the race gas, overheating problems, ear ringing noise, and POLICE CHECK every 2 miles.
Rick L. Ps if you want to go racing, build a windsor stroker, cost less to build and break. Cheaper than a FE based motor. Can get the same power you are looking for with a higher rpm range. IMO, I am not a fan of spinning heavy bottom end motors more than 6,500 rpms. FE rod motors run small rod bearings as compared to other cars with the same rotating mass wieght. This is why the stroker kits are running BBC rods, wider bearings to handle the loads.