[Flathill]

I think you need the Vacuum Tube Line with end part # 21A-12226 that fits to the manifold connection under the carburetor. The connection on the intake manifold takes the tube with a ring end from the vacuum brake on the distributor and the rubber tube from the windshield wiper.

Refer to the thread titled "intake manifold vacuum 59ab" dated 04-20-2013 by Thaplumbr. Also there is a good picture.
The Tube line can be purchased from Joe's Antique Auto, C&A and others.

The connection that screws into the manifold under the carburetor has a hole in it with 2 copper gaskets. This fitting I can not find on line.

You can test run the engine without the vacuum tube connected but you should hook up the tube and vacuum brake on the distributor later for better engine performance.