318 MAX fuel economy builds?

I would keep the coolant cross-over, but dimple the floor of the plenum under the carb. Keep the intake ports as rough as possible. There is a thread somewhere on this site about slightly bending a carbide bit and having it chatter across the surface to tear it up. Wet flow provides a unique opportunity to give the fuel more time to vaporize (or fall out of suspension if not done properly). Here is a SBC intake with the sides carved with Powre Lynz and the floor dimpled.
intakeplenum1.jpg