I would run a single plane if it were mine.

I have a 402 magnum headed engine and have a M1 single plane for it.

That Air gap isnt a good intake for a max ported, 6800 rpm 408 cid engine IMO.


67 Barracuda street/bracket car 11.27-119
68 Dart 502 BB 8.70s-152
414 cid SB Dragster 7.65-174