littlewave This is about what the real reading are, if dynoed. What you are REALLY looking for is TORQUE. This is what moves your car from still to what mph you want. HP is the top number your motor makes and is used at top end for high speeds. It sound like you have a nice car that will run good and last if you keep control of your right foot. I wouldn't recomend you drag race a T-5 trans. If you roll off the start line this will not abuse the trans. If you 3,000 rpm holeshot the car, trans or clutch with suffer.
As far as the 500-600hp motors heard on the forum, don't believe everything you hear. I have a 482 motor with 610 ft of tork and 560 HP. This goes to 420 rwhp and 480ft of tork. This is fast enough to have the car run low 11.0's if the tires would hook.
True drivetrain loss is about 15-22% depending on rearend, trans, what you are running off the motor, Alt, Waterpump, P/s, drysump
oil pumps,and ac compressor. These all drain power.
Until you become a driver, you really don't need 500 hp. There are many a cobra owners here and a few that have died from having too much power and not rescept these cars. Cobras are fast, bural, unforgiving, and react faster than most drivers. Short wheel base also adds to the handling issues. The best orginial drivers say that 500 horse and 600 ft of tork are a safe limit. There are guys running real 700HP at the rear wheels. These are race cars with plates. You will catch the power bug over time, we all do. I went from a 452 to 482 to a 498 nasty motor. It's been a 15 year learning leason and worth the trip is you just remember safety first and know your limits. Driving schools are also a big help. Rick L.