Several years ago, I fabricated a balance tube between the venturis of a Weber carburetor for an MGB so intake manifold pulsations would dampen out a little. I used a piece of white oak wood. It can be worked with a bandsaw and a belt sander, and it's dense enough to accept threads from a pipe tap. The vacuum nipple could also be a press fit in a drilled hole, secured by epoxy. Hickory or Mahogany might also be possible options. You can bore an accurate hole for the main passage with a Forstner bit in a drill press. Once the prototype is built, you can decide whether or not to continue to run it, or use it as a pattern to duplicate the part in aluminum or phenolic.
Jerry
