Wich axel is the best for me?

Hy i own a 72`Dodge Dart 318 with a 7 1/4 rear axel.

I am about to do an Engine swap to something about 408 Cui Magnum.

Wich axel should i build in the car. My goal for the axel are:

1. it should stand the power of the motor 400-500 hp
2. should be as light as possible
3. should be an affordable price.
4. Dont hafe to be original part, can be aftermarket to...

Wich axel? where to buy it?

thanks for your advises!