I plan on getting a 9" currie enterpize rear from jegs for mine. They are the strongest and are direct fit for the car. But they cost around $2000 for everthing. Don't even consider the 8" I just blow my secound one with a worn out stock 302. The only mod to the engine is I put a 600 holley carb on it.

 

ok, reality check time...

do you really know what 500hp is???
If you think you can build diff, suspension and brakes for a currently stock car to handle 500hp with$1700- I'm sorry, you are dreaming. As others have posted, that wont even get the rear you need.

Believe me, without the brakes you wont live long if you have 500hp.

a 300hp 302 with 3.55 gears ina67/68coupe will feel like an F18 compared to stock. I dont wanna be the fun police, but you should consider this build as a project over time...to add as you can afford.

Start with brakes and suspension, add drivetrain and do engine last. You will then have a much better understanding of what change had what impact and be so much more capable of driving the car if/when you do finally go for the big hp engine.