727 Rebuild help

So I have a 727 that I will need to have rebuilt to go behind a warmed over 440 and Dana 60 rear. What will it need done to it?? I would guess that the final HP will be somewhere around 500hp in a street driving car. What parts do I need to get this done? I plan to take it to a builder but I like to buy my parts little by little.

Why not let the builder buy the parts?