What would be the best rear end?

I have a 1973 Swinger that currently has a 318 but I do plan on running a stroked 360 eventually. I am looking for a posi rear end, or sure grip, what would be the best recommendation? Im looking for a bolt in, ready to go, thats under $500.

Robert
You are talking about a complete rear axle with a sure grip in it for $500? Good luck......