The Intake's came in 2 flavors: Aluminum and Iron
Due to poor workmanship on the Aluminum ones, the Iron intake is the 1 to find/use.
I have 4 Super Six setups out in the shop, but their all earmarked for projects.
If you can't find anything in the local yards, check Craigslist. I just bought the 78 Aspen sedan for $500 locally....I bought it mainly for interchangable parts for my Aspen wagon, The Super Six setup was a bonus and not uncommon in these cars.
Once you find a setup, I highly recommend National Carburetor for sourcing a carb if you don't have a good one, and the Electric choke #1232 from BFIC Carbsonly
for a Intake and exhaust gasket - nothing beats Remflex 6008 and 6006
Use the 2.25 exhaust gasket as a pattern and hog out the manifold to match, Add a 2.25 exhaust and your in good shape
Next thing would be to dial in your timing with a custom tune - you can contact
[email protected] for a spring kit he makes for Slant 6's.
Only other things left on the table of easy is - shaving the head for a CC boost and Multi-spark ignition.