Why only a 1/2"? Magster, looks like you went 3/4"? Why not take the plenum all the way down to the top "floor" of the runners?
What would happen if you removed the entire plenum so the carb opening looked like a single plane opening? One large square hole (with rounded corners).
The old MP books show this mod for the LD-340. They left some meet in the divider. The divider was milled down to 3/8 of an inch from wall to wall on a front to rear direction. All walls of the divider are rounded.
With the RPM intake, Edelbrock has less of a deep cut. (It’s actually cast in) on the Chevy intake. I would start with a copy of the Chevy dimensions on the center divider milling. Then see how it performs. It is easier to remove than replace the aluminum.
