SOLVED! 318 2500-3000 rpm idling issue. Don't think its a regular vacuum leak. Swapped 2 intakes, 2 carbs ,and 6 different gaskets still no luck.

I have had the rivet issue, caught it when I set the head on and it rocked. Leak down should determine if it is pulling air in through there. Does the brawler have an air screw that takes the place of drilling holes in the throttle plates. I know my mighty demon had one I think under the air cleaner stud.