I bought a rubber plug from Carquest can't remember what the size was and ok that's cool with the 3/8 adapters and I have a 1" spacer in my intake and it barely clears the systemax cover also for what it's worth I have the baffle in mine and still had oil in my throttle body.

this thing for now put the expandable plug in and run with my filter on the valve cover until I do the whole setup