Quad carb setup information help
The hole in the cap has to be bigger than the hole in the Unisyn so the hole isn’t the restriction.
You can use Right Stuff silicone to stick the Unisyn to the cap.
You shouldn’t need a gasket, but I’ve been using a plastic cap. You can feel the engine suck the cap down on the carb. If you use the aluminum cap, you may need a gasket.