Hello. Need to pick your brains about best intake manifold on 406 sbc with extremely ported fuelie heads. Currently reinstalling this 406 into a 65 c10 2wd after harmonic balancer walked off crankshaft a high RPM's. Made a mess but crank was not damaged so back in it goes. When I put this motor together I changed 76 cc heads for 461 fuelies with 202 valves to up the compression. These heads were ported to a knife edge between intake runners and set up for roller rockers. Currently running 480 lift cam and 1.6 rockers. Selected a c4b edelbrock from intake collection as it had biggest runners and front oil fill tube for period look. Give me your ideas on highest flowing dual plane intake manifolds. I have Air Gaps, 7101 rpms and holley 300-36 z28 clones that I am considering. Seat of pants performance and torque was unreal with antiquated c4b. Thank you.
Go to the drag strip, run the truck, swap intakes, go back to the drag strip, see what worked best. But it sounds like you have an engine that really needs an old intake on it to look right, so the air gap should stay on the shelf, where it belongs.
The Air gap will make the most power. But the regular performer rpm with an 1" open spacer looks more right and will make almost identical power.