Best Intake for a 408

The best dual purpose all around intake is the RPM.
Depending on the camshaft and the head flow specs, or AKA, a well ported head over a stock or mildly modified head, the single plane intake would be the better choice for the top end and probably not a loss down low ether. There could be a 40+ hp gain.

But again, how well the heads are ported and the cam being used has a ton of say in that.