to make 500 HP with right at 500 FT Lbs. with a stock stroke 440 on pump gas may be harder to keep the torque even with the HP, normally the stock stroke motors with less than 10.5 to 1 compression all made 20 to 50 ft. lbs. more torque than HP
The parts you need to make 500+ HP and torque are a decent set of aluminum heads and a good set of adjustable rockers, pistons that will make between 10.to 1 and 10.5 to 1 compression, a 850 CFM or larger carb., a Eddy Performer RPM intake and a decent cam with between 235 to 250 degrees @ .050 duration and as much lift as you can get at the valves and a decent set of headers and a minimum of 2.5 exhaust system on the car with a good set of Hi Po muffs
That formula works good on midly ported Mopar iron heads with 2.14 and 1.81 valves with under 9.5 to 1 compression ratio so with the better aluminum heads like the Eddy RPM and the increase in compression you should be nearer 550 HP than 500 HP
Let us know what you decide to do, a good SB stroker will work well also so compare the costs and effort needed before deciding