Well, it looks like you've already put in the 351W. It's difficult to answer your question because you haven't stated the body style or whether its a stock 351W or not. If has a stock bottom end, forget about 500 hp, especially if has stock heads, exhaust, etc. If you put a blower on, to try and get to 500 hp, you had better plan on replacing the motor fairly soon.
I hope you have deep pockets, because another problem will be to get the power to the ground. However, if its a drag only car you can totally gut the car to make up for the additional weight of the 351 over the 302; meaning removing radio, back seats, and anything else to take get the weight down to 2800 to 3000 lb, driver included.
I'm still not sure why their is this stigma attached to stroker motors, but I can guarantee that a properly prep stroker will spank a low boost stock motor 351, and unless you're getting the blower pretty cheap (meaning a used one) the cost of a decent blower would get you into a pretty decently stroked 351. Your info is way too sketchy to give you any more advise. Sorry.
__________________ ‘88 LX Hatchback: 351 stroked to 408 w/4 bolt mains & steel crank, 12.5 :1 forged pistons, Cartech “Bread Box” upper/Edelbrock lower(ported and polished), BBK 75 mm Mass Air w/120 lb injectors, Dart II ported, polished O-ringed 2.02/1.60 heads, Custom Competition Cam hydraulic roller w/Roads lifters, Hypertech custom chip, 1100 hp Aeromotive Competition fuel kit, 9” w/ 4.86’s, Tremec T56 six speed, , Hotchkis performance suspension, 400 shot of nitrous. Passes emissions running E85. | 
