i had the exact same car, i achieved 475 at the rear wheels with a stock bottom end, the stock bottom end is good for about 525 hp at the crank, and for your car the easiest way to get that power is convert to mas air and run a turbo kit at about 5-8 lbs of boost, remember that at 14.7 lbs of boost you double your all motor hp! (with the correct amount of fuel) so if you have 225 hp at the rear wheels then 14.7 lbs of boost will make about 450hp, any mods to the all motor before boost will add up big time. a head swap that makes 50 extra hp will be good for 100hp at 14.7 lbs of boost.