I thought of using aluminum, and I have some plastic carb spacers I could use with it for insulation, but I was worried that the carb mounting screws themselves would transfer enough heat to be a problem. That's why all the stock manifold insulators use two bolts to mount the insulator, and two different bolts that attach only to the insulator to attach the carb. It doesn't allow a heat path from the engne to the carb through the mounting screws.

AV8TOR