Intake vacume hardware

The fitting on the booster IS a checkvalve.
If you don't have it, and it's grommet, IDK where to get it except I'd "borrow" one off one of my junker-cars,lol.
On the intake side anything goes, no checkvalve required. But do not use fuel line for the connecting hose; the engine will vacuum it flat. You need the proper thick-wall vacuum hose to fit your checkvalve, and to fit the corresponding intake fitting, with it's hose barb.