Hyper Pak vs Super Six
The original hyper pac intake is very difficult to find. There is a guy that brings one and the original cast headers to Carlisle every year but he wants 0ver $2K for them. Clifford makes a repop hyper pac intake but what I have heard is that you could wait up to a year to get you part after your card is charged.
You would be much happier with a Clifford 4bbl intake or an Offie 4bbl intake. They are made to use the stock exhaust manifold heat. If you haven't modified your slant in any way(porting, larger valves, compression) then a 4bbl is really over kill. you will never be using the secondaries.
For a stock engine a super six is your best bet. They are still plentiful in the yards near me. I can think of at least 3 off the top of my head. The BBD is a very user friendly carb to tune and you will notice a nice improvement in performance.