You guys must HATE answering thse same questions over and over and over every time one of us new guys visits with all these questions but it's your job as experts so take a deep breath and please make you November installment on these FAQ..
My combo [again]

1969 w/ PS PB A/C
496 10.3:1
781 2.18 valves [Oval OC 118CC]
3:23 turbo 400 w/2000 stall conv.

Still haven't talked to UDHarold about a cam but whatever he chooses must idle.

If you can answer these couple questions.. I'll stop...

Headers 1 7/8 ok? Or do I need 2 inch I can get either.

Carb. Gotta have a choke...Avenger? 850 DP? Something else? A vacuum secondary carb scares me...

Intake. I own a C-396 any difference between the other dual planes? Not sure there is room for an Air gap...
you talk...I listen..Thanks

Use a vacuum carb. I like the C-396 better than the newer stuff but I have not seen one on a flow bench.

i'd definately run the Air Gap and a dp carb around an 800-850. and i would say with that many cubes the 2" S/C headers. just my opinion though, and i'm no expert. ;)