I'd find a stock or Offy or Wyand or old edelbrock and baseline before spending that kind of coin on a new manifold, even a dual quad with a couple of AVS
spend the rest of the money on some headers and good duals, transgo kit, etc
remember polys do not need much cam
might not fit and not be for your gears/ converter/ cam/ goals
come up with a list of OK and Pass on
join some Poly groups
It's a strong motor- takes all kind of abuse, works hard, runs forever
be patient in your search